diff --git a/app/controllers/api/cart_controller.rb b/app/controllers/api/cart_controller.rb
index 5b150a70e..829bd29bb 100644
--- a/app/controllers/api/cart_controller.rb
+++ b/app/controllers/api/cart_controller.rb
@@ -52,6 +52,6 @@ class API::CartController < API::ApiController
   private
 
   def orderable
-    Product.find(cart_params[:orderable_id])
+    params[:orderable_type].classify.constantize.find(cart_params[:orderable_id])
   end
 end
diff --git a/app/controllers/api/payments_controller.rb b/app/controllers/api/payments_controller.rb
index 30cb5aa6c..7a878ee86 100644
--- a/app/controllers/api/payments_controller.rb
+++ b/app/controllers/api/payments_controller.rb
@@ -41,6 +41,7 @@ class API::PaymentsController < API::ApiController
       { json: res[:errors].drop_while(&:empty?), status: :unprocessable_entity }
     end
   rescue StandardError => e
+    Rails.logger.debug e.backtrace
     { json: e, status: :unprocessable_entity }
   end
 end
diff --git a/app/exceptions/cart/unknown_item_error.rb b/app/exceptions/cart/unknown_item_error.rb
new file mode 100644
index 000000000..b47b4c18f
--- /dev/null
+++ b/app/exceptions/cart/unknown_item_error.rb
@@ -0,0 +1,5 @@
+# frozen_string_literal: true
+
+# Raised when the added item is not a recognized class
+class Cart::UnknownItemError < StandardError
+end
diff --git a/app/frontend/src/javascript/api/cart.ts b/app/frontend/src/javascript/api/cart.ts
index 1f5627cd9..eeb89976b 100644
--- a/app/frontend/src/javascript/api/cart.ts
+++ b/app/frontend/src/javascript/api/cart.ts
@@ -1,6 +1,6 @@
 import apiClient from './clients/api-client';
 import { AxiosResponse } from 'axios';
-import { Order, OrderErrors } from '../models/order';
+import { Order, OrderableType, OrderErrors } from '../models/order';
 
 export default class CartAPI {
   static async create (token?: string): Promise<Order> {
@@ -8,28 +8,28 @@ export default class CartAPI {
     return res?.data;
   }
 
-  static async addItem (order: Order, orderableId: number, quantity: number): Promise<Order> {
-    const res: AxiosResponse<Order> = await apiClient.put('/api/cart/add_item', { order_token: order.token, orderable_id: orderableId, quantity });
+  static async addItem (order: Order, orderableId: number, orderableType: OrderableType, quantity: number): Promise<Order> {
+    const res: AxiosResponse<Order> = await apiClient.put('/api/cart/add_item', { order_token: order.token, orderable_id: orderableId, orderable_type: orderableType, quantity });
     return res?.data;
   }
 
-  static async removeItem (order: Order, orderableId: number): Promise<Order> {
-    const res: AxiosResponse<Order> = await apiClient.put('/api/cart/remove_item', { order_token: order.token, orderable_id: orderableId });
+  static async removeItem (order: Order, orderableId: number, orderableType: OrderableType): Promise<Order> {
+    const res: AxiosResponse<Order> = await apiClient.put('/api/cart/remove_item', { order_token: order.token, orderable_id: orderableId, orderable_type: orderableType });
     return res?.data;
   }
 
-  static async setQuantity (order: Order, orderableId: number, quantity: number): Promise<Order> {
-    const res: AxiosResponse<Order> = await apiClient.put('/api/cart/set_quantity', { order_token: order.token, orderable_id: orderableId, quantity });
+  static async setQuantity (order: Order, orderableId: number, orderableType: OrderableType, quantity: number): Promise<Order> {
+    const res: AxiosResponse<Order> = await apiClient.put('/api/cart/set_quantity', { order_token: order.token, orderable_id: orderableId, orderable_type: orderableType, quantity });
     return res?.data;
   }
 
-  static async setOffer (order: Order, orderableId: number, isOffered: boolean): Promise<Order> {
-    const res: AxiosResponse<Order> = await apiClient.put('/api/cart/set_offer', { order_token: order.token, orderable_id: orderableId, is_offered: isOffered, customer_id: order.user?.id });
+  static async setOffer (order: Order, orderableId: number, orderableType: OrderableType, isOffered: boolean): Promise<Order> {
+    const res: AxiosResponse<Order> = await apiClient.put('/api/cart/set_offer', { order_token: order.token, orderable_id: orderableId, orderable_type: orderableType, is_offered: isOffered, customer_id: order.user?.id });
     return res?.data;
   }
 
-  static async refreshItem (order: Order, orderableId: number): Promise<Order> {
-    const res: AxiosResponse<Order> = await apiClient.put('/api/cart/refresh_item', { order_token: order.token, orderable_id: orderableId });
+  static async refreshItem (order: Order, orderableId: number, orderableType: OrderableType): Promise<Order> {
+    const res: AxiosResponse<Order> = await apiClient.put('/api/cart/refresh_item', { order_token: order.token, orderable_id: orderableId, orderable_type: orderableType });
     return res?.data;
   }
 
diff --git a/app/frontend/src/javascript/components/cart/store-cart.tsx b/app/frontend/src/javascript/components/cart/store-cart.tsx
index 869e2cf80..6ff701989 100644
--- a/app/frontend/src/javascript/components/cart/store-cart.tsx
+++ b/app/frontend/src/javascript/components/cart/store-cart.tsx
@@ -65,7 +65,7 @@ const StoreCart: React.FC<StoreCartProps> = ({ onSuccess, onError, currentUser,
       if (errors.length === 1 && errors[0].error === 'not_found') {
         reloadCart().catch(onError);
       } else {
-        CartAPI.removeItem(cart, item.orderable_id).then(data => {
+        CartAPI.removeItem(cart, item.orderable_id, item.orderable_type).then(data => {
           setCart(data);
         }).catch(onError);
       }
@@ -76,7 +76,7 @@ const StoreCart: React.FC<StoreCartProps> = ({ onSuccess, onError, currentUser,
    * Change product quantity
    */
   const changeProductQuantity = (e: React.BaseSyntheticEvent, item) => {
-    CartAPI.setQuantity(cart, item.orderable_id, e.target.value)
+    CartAPI.setQuantity(cart, item.orderable_id, item.orderable_type, e.target.value)
       .then(data => {
         setCart(data);
       })
@@ -87,7 +87,7 @@ const StoreCart: React.FC<StoreCartProps> = ({ onSuccess, onError, currentUser,
    * Increment/decrement product quantity
    */
   const increaseOrDecreaseProductQuantity = (item, direction: 'up' | 'down') => {
-    CartAPI.setQuantity(cart, item.orderable_id, direction === 'up' ? item.quantity + 1 : item.quantity - 1)
+    CartAPI.setQuantity(cart, item.orderable_id, item.orderable_type, direction === 'up' ? item.quantity + 1 : item.quantity - 1)
       .then(data => {
         setCart(data);
       })
@@ -101,7 +101,7 @@ const StoreCart: React.FC<StoreCartProps> = ({ onSuccess, onError, currentUser,
     return (e: React.BaseSyntheticEvent) => {
       e.preventDefault();
       e.stopPropagation();
-      CartAPI.refreshItem(cart, item.orderable_id).then(data => {
+      CartAPI.refreshItem(cart, item.orderable_id, item.orderable_type).then(data => {
         setCart(data);
       }).catch(onError);
     };
@@ -185,7 +185,7 @@ const StoreCart: React.FC<StoreCartProps> = ({ onSuccess, onError, currentUser,
     // if the selected user is the operator, he cannot offer products to himself
     if (user.id === currentUser.id && cart.order_items_attributes.filter(item => item.is_offered).length > 0) {
       Promise.all(cart.order_items_attributes.filter(item => item.is_offered).map(item => {
-        return CartAPI.setOffer(cart, item.orderable_id, false);
+        return CartAPI.setOffer(cart, item.orderable_id, item.orderable_type, false);
       })).then((data) => setCart({ ...data[data.length - 1], user: { id: user.id, role: user.role } }));
     } else {
       setCart({ ...cart, user: { id: user.id, role: user.role } });
@@ -211,7 +211,7 @@ const StoreCart: React.FC<StoreCartProps> = ({ onSuccess, onError, currentUser,
    */
   const toggleProductOffer = (item) => {
     return (checked: boolean) => {
-      CartAPI.setOffer(cart, item.orderable_id, checked).then(data => {
+      CartAPI.setOffer(cart, item.orderable_id, item.orderable_type, checked).then(data => {
         setCart(data);
       }).catch(e => {
         if (e.match(/code 403/)) {
diff --git a/app/frontend/src/javascript/components/reservations/reservations-summary.tsx b/app/frontend/src/javascript/components/reservations/reservations-summary.tsx
new file mode 100644
index 000000000..ed60c4776
--- /dev/null
+++ b/app/frontend/src/javascript/components/reservations/reservations-summary.tsx
@@ -0,0 +1,64 @@
+import { IApplication } from '../../models/application';
+import React, { useEffect } from 'react';
+import { Loader } from '../base/loader';
+import { react2angular } from 'react2angular';
+import type { Slot } from '../../models/slot';
+import { useImmer } from 'use-immer';
+import FormatLib from '../../lib/format';
+import { FabButton } from '../base/fab-button';
+import { ShoppingCart } from 'phosphor-react';
+import CartAPI from '../../api/cart';
+import useCart from '../../hooks/use-cart';
+import type { User } from '../../models/user';
+
+declare const Application: IApplication;
+
+interface ReservationsSummaryProps {
+  slot: Slot,
+  customer: User,
+  onError: (error: string) => void,
+}
+
+/**
+ * Display a summary of the selected slots, and ask for confirmation before adding them to the cart
+ */
+const ReservationsSummary: React.FC<ReservationsSummaryProps> = ({ slot, customer, onError }) => {
+  const { cart, setCart } = useCart(customer);
+  const [pendingSlots, setPendingSlots] = useImmer<Array<Slot>>([]);
+
+  useEffect(() => {
+    if (slot) {
+      if (pendingSlots.find(s => s.slot_id === slot.slot_id)) {
+        setPendingSlots(draft => draft.filter(s => s.slot_id !== slot.slot_id));
+      } else {
+        setPendingSlots(draft => { draft.push(slot); });
+      }
+    }
+  }, [slot]);
+
+  /**
+   * Add the product to cart
+   */
+  const addSlotToCart = (slot: Slot) => {
+    return () => {
+      CartAPI.addItem(cart, slot.slot_id, 'Slot', 1).then(setCart).catch(onError);
+    };
+  };
+
+  return (
+    <ul>{pendingSlots.map(slot => (
+      <li key={slot.slot_id}>
+        <span>{FormatLib.date(slot.start)} {FormatLib.time(slot.start)} - {FormatLib.time(slot.end)}</span>
+        <FabButton onClick={addSlotToCart(slot)}><ShoppingCart size={24}/> add to cart </FabButton>
+      </li>
+    ))}</ul>
+  );
+};
+
+const ReservationsSummaryWrapper: React.FC<ReservationsSummaryProps> = (props) => (
+  <Loader>
+    <ReservationsSummary {...props} />
+  </Loader>
+);
+
+Application.Components.component('reservationsSummary', react2angular(ReservationsSummaryWrapper, ['slot', 'customer', 'onError']));
diff --git a/app/frontend/src/javascript/components/store/store-product-item.tsx b/app/frontend/src/javascript/components/store/store-product-item.tsx
index eb1c42145..2afaaf7e1 100644
--- a/app/frontend/src/javascript/components/store/store-product-item.tsx
+++ b/app/frontend/src/javascript/components/store/store-product-item.tsx
@@ -40,7 +40,7 @@ export const StoreProductItem: React.FC<StoreProductItemProps> = ({ product, car
   const addProductToCart = (e: React.BaseSyntheticEvent) => {
     e.preventDefault();
     e.stopPropagation();
-    CartAPI.addItem(cart, product.id, 1).then(onSuccessAddProductToCart).catch(() => {
+    CartAPI.addItem(cart, product.id, 'Product', 1).then(onSuccessAddProductToCart).catch(() => {
       onError(t('app.public.store_product_item.stock_limit'));
     });
   };
diff --git a/app/frontend/src/javascript/components/store/store-product.tsx b/app/frontend/src/javascript/components/store/store-product.tsx
index 8175e7acc..ba3268479 100644
--- a/app/frontend/src/javascript/components/store/store-product.tsx
+++ b/app/frontend/src/javascript/components/store/store-product.tsx
@@ -108,7 +108,7 @@ export const StoreProduct: React.FC<StoreProductProps> = ({ productSlug, current
    */
   const addToCart = () => {
     if (toCartCount <= product.stock.external) {
-      CartAPI.addItem(cart, product.id, toCartCount).then(data => {
+      CartAPI.addItem(cart, product.id, 'Product', toCartCount).then(data => {
         setCart(data);
         onSuccess(t('app.public.store_product.add_to_cart_success'));
       }).catch(() => {
diff --git a/app/frontend/src/javascript/controllers/machines.js.erb b/app/frontend/src/javascript/controllers/machines.js.erb
index 16e19d276..de25fed88 100644
--- a/app/frontend/src/javascript/controllers/machines.js.erb
+++ b/app/frontend/src/javascript/controllers/machines.js.erb
@@ -393,12 +393,6 @@ Application.Controllers.controller('ReserveMachineController', ['$scope', '$tran
     // Slot free to be booked
     const FREE_SLOT_BORDER_COLOR = '<%= AvailabilityHelper::MACHINE_COLOR %>';
 
-    // Slot already booked by another user
-    const UNAVAILABLE_SLOT_BORDER_COLOR = '<%= AvailabilityHelper::MACHINE_IS_RESERVED_BY_USER %>';
-
-    // Slot already booked by the current user
-    const BOOKED_SLOT_BORDER_COLOR = '<%= AvailabilityHelper::IS_RESERVED_BY_CURRENT_USER %>';
-
     /* PUBLIC SCOPE */
 
     // bind the machine availabilities with full-Calendar events
@@ -642,7 +636,6 @@ Application.Controllers.controller('ReserveMachineController', ['$scope', '$tran
      * Callback triggered after a successful prepaid-pack purchase
      */
     $scope.onSuccess = function (message) {
-
       growl.success(message);
     };
 
diff --git a/app/frontend/src/javascript/models/order.ts b/app/frontend/src/javascript/models/order.ts
index 08d9d53bf..c82e33df6 100644
--- a/app/frontend/src/javascript/models/order.ts
+++ b/app/frontend/src/javascript/models/order.ts
@@ -5,6 +5,8 @@ import { UserRole } from './user';
 import { Coupon } from './coupon';
 import { ApiFilter, PaginatedIndex } from './api';
 
+export type OrderableType = 'Product' | 'Slot';
+
 export interface Order {
   id: number,
   token: string,
@@ -28,7 +30,7 @@ export interface Order {
   paid_total?: number,
   order_items_attributes: Array<{
     id: number,
-    orderable_type: string,
+    orderable_type: OrderableType,
     orderable_id: number,
     orderable_name: string,
     orderable_slug: string,
diff --git a/app/frontend/src/javascript/models/slot.ts b/app/frontend/src/javascript/models/slot.ts
new file mode 100644
index 000000000..e62129898
--- /dev/null
+++ b/app/frontend/src/javascript/models/slot.ts
@@ -0,0 +1,50 @@
+import { TDateISO } from '../typings/date-iso';
+
+export interface Slot {
+  slot_id: number,
+  can_modify: boolean,
+  title: string,
+  start: TDateISO,
+  end: TDateISO,
+  is_reserved: boolean,
+  is_completed: boolean,
+  backgroundColor: 'white',
+
+  availability_id: number,
+  slots_reservations_ids: Array<number>,
+  tag_ids: Array<number>,
+  tags: Array<{
+    id: number,
+    name: string,
+  }>
+  plan_ids: Array<number>,
+
+  // the users who booked on this slot, if any
+  users: Array<{
+    id: number,
+    name: string
+  }>,
+
+  borderColor?: '#eeeeee' | '#b2e774' | '#e4cd78' | '#bd7ae9' | '#dd7e6b' | '#3fc7ff' | '#000',
+  // machine
+  machine?: {
+    id: number,
+    name: string
+  },
+  // training
+  nb_total_places?: number,
+  training?: {
+    id: number,
+    name: string,
+    description: string,
+    machines: Array<{
+      id: number,
+      name: string
+    }>
+  },
+  // space
+  space?: {
+    id: number,
+    name: string
+  }
+}
diff --git a/app/frontend/templates/machines/reserve.html b/app/frontend/templates/machines/reserve.html
index 785ba2cee..b0b9d6aed 100644
--- a/app/frontend/templates/machines/reserve.html
+++ b/app/frontend/templates/machines/reserve.html
@@ -2,16 +2,22 @@
 
 <section class="heading b-b">
   <div class="row no-gutter">
-    <div class="col-xs-2 col-sm-2 col-md-1">
+    <div class="col-xs-2 col-md-1">
       <section class="heading-btn">
         <a ng-click="backPrevLocation($event)"><i class="fas fa-long-arrow-alt-left "></i></a>
       </section>
     </div>
-    <div class="col-xs-10 col-sm-10 col-md-8 b-l">
+    <div class="col-xs-8 col-md-10 b-l">
       <section class="heading-title">
         <h1>{{ 'app.logged.machines_reserve.machine_planning' | translate }} : {{machine.name}}</h1>
       </section>
     </div>
+
+    <div class="col-xs-2 col-md-1 b-t hide-b-md p-none">
+      <section class="heading-actions">
+        <cart-button />
+      </section>
+    </div>
   </div>
 </section>
 
@@ -39,6 +45,8 @@
                    refresh="afterPaymentPromise">
     </packs-summary>
 
+    <reservations-summary slot="selectedEvent" customer="ctrl.member" on-error="onError"></reservations-summary>
+
     <cart slot="selectedEvent"
           slot-selection-time="selectionTime"
           events="events"
diff --git a/app/helpers/availability_helper.rb b/app/helpers/availability_helper.rb
index 9d05176ab..ec49741d0 100644
--- a/app/helpers/availability_helper.rb
+++ b/app/helpers/availability_helper.rb
@@ -7,7 +7,6 @@ module AvailabilityHelper
   SPACE_COLOR = '#3fc7ff'
   EVENT_COLOR = '#dd7e6b'
   IS_RESERVED_BY_CURRENT_USER = '#b2e774'
-  MACHINE_IS_RESERVED_BY_USER = '#1d98ec'
   IS_FULL = '#eeeeee'
 
   def availability_border_color(availability)
diff --git a/app/models/cart_item/base_item.rb b/app/models/cart_item/base_item.rb
index 25d829785..9e4a04ce1 100644
--- a/app/models/cart_item/base_item.rb
+++ b/app/models/cart_item/base_item.rb
@@ -1,15 +1,15 @@
 # frozen_string_literal: true
 
 # Items that can be added to the shopping cart
-module CartItem; end
+module CartItem
+  def self.table_name_prefix
+    'cart_item_'
+  end
+end
 
 # This is an abstract class implemented by classes that can be added to the shopping cart
-class CartItem::BaseItem
-  attr_reader :errors
-
-  def initialize(*)
-    @errors = {}
-  end
+class CartItem::BaseItem < ApplicationRecord
+  self.abstract_class = true
 
   def price
     { elements: {}, amount: 0 }
diff --git a/app/models/cart_item/coupon.rb b/app/models/cart_item/coupon.rb
index 8506e35c3..51767727d 100644
--- a/app/models/cart_item/coupon.rb
+++ b/app/models/cart_item/coupon.rb
@@ -1,20 +1,17 @@
 # frozen_string_literal: true
 
 # A discount coupon applied to the whole shopping cart
-class CartItem::Coupon
-  attr_reader :errors
+class CartItem::Coupon < ApplicationRecord
+  belongs_to :operator_profile, class_name: 'InvoicingProfile'
+  belongs_to :customer_profile, class_name: 'InvoicingProfile'
+  belongs_to :coupon
 
-  # @param coupon {String|Coupon} may be nil or empty string if no coupons are applied
-  def initialize(customer, operator, coupon)
-    @customer = customer
-    @operator = operator
-    @coupon = coupon
-    @errors = {}
+  def operator
+    operator_profile.user
   end
 
-  def coupon
-    cs = CouponService.new
-    cs.validate(@coupon, @customer.id)
+  def customer
+    customer_profile.user
   end
 
   def price(cart_total = 0)
@@ -31,11 +28,10 @@ class CartItem::Coupon
   end
 
   def valid?(_all_items)
-    return true if @coupon.nil?
+    return true if coupon.nil?
 
-    c = ::Coupon.find_by(code: @coupon)
-    if c.nil? || c.status(@customer.id) != 'active'
-      @errors[:item] = 'coupon is invalid'
+    if coupon.status(customer.id) != 'active'
+      errors.add(:coupon, 'invalid coupon')
       return false
     end
     true
diff --git a/app/models/cart_item/event_reservation.rb b/app/models/cart_item/event_reservation.rb
index 4e6796243..a13e03b8b 100644
--- a/app/models/cart_item/event_reservation.rb
+++ b/app/models/cart_item/event_reservation.rb
@@ -2,30 +2,38 @@
 
 # An event reservation added to the shopping cart
 class CartItem::EventReservation < CartItem::Reservation
-  # @param normal_tickets {Number} number of tickets at the normal price
-  # @param other_tickets {Array<{booked: Number, event_price_category_id: Number}>}
-  def initialize(customer, operator, event, slots, normal_tickets: 0, other_tickets: [])
-    raise TypeError unless event.is_a? Event
+  has_many :cart_item_event_reservation_tickets, class_name: 'CartItem::EventReservationTicket', dependent: :destroy,
+                                                 inverse_of: :cart_item_event_reservation,
+                                                 foreign_key: 'cart_item_event_reservation_id'
+  accepts_nested_attributes_for :cart_item_event_reservation_tickets
 
-    super(customer, operator, event, slots)
-    @normal_tickets = normal_tickets || 0
-    @other_tickets = other_tickets || []
+  has_many :cart_item_reservation_slots, class_name: 'CartItem::ReservationSlot', dependent: :destroy, inverse_of: :cart_item,
+                                         foreign_key: 'cart_item_id', foreign_type: 'cart_item_type'
+  accepts_nested_attributes_for :cart_item_reservation_slots
+
+  belongs_to :operator_profile, class_name: 'InvoicingProfile'
+  belongs_to :customer_profile, class_name: 'InvoicingProfile'
+
+  belongs_to :event
+
+  def reservable
+    event
   end
 
   def price
-    amount = @reservable.amount * @normal_tickets
-    is_privileged = @operator.privileged? && @operator.id != @customer.id
+    amount = reservable.amount * normal_tickets
+    is_privileged = operator.privileged? && operator.id != customer.id
 
-    @other_tickets.each do |ticket|
-      amount += ticket[:booked] * EventPriceCategory.find(ticket[:event_price_category_id]).amount
+    cart_item_event_reservation_tickets.each do |ticket|
+      amount += ticket.booked * ticket.event_price_category.amount
     end
 
     elements = { slots: [] }
     total = 0
 
-    @slots.each do |slot|
+    cart_item_reservation_slots.each do |sr|
       total += get_slot_price(amount,
-                              slot,
+                              sr,
                               is_privileged,
                               elements: elements,
                               is_division: false)
@@ -36,26 +44,25 @@ class CartItem::EventReservation < CartItem::Reservation
 
   def to_object
     ::Reservation.new(
-      reservable_id: @reservable.id,
+      reservable_id: reservable.id,
       reservable_type: Event.name,
       slots_reservations_attributes: slots_params,
-      tickets_attributes: tickets_params,
-      nb_reserve_places: @normal_tickets,
-      statistic_profile_id: StatisticProfile.find_by(user: @customer).id
+      tickets_attributes: cart_item_event_reservation_tickets.map do |t|
+        {
+          event_price_category_id: t.event_price_category_id,
+          booked: t.booked
+        }
+      end,
+      nb_reserve_places: normal_tickets,
+      statistic_profile_id: StatisticProfile.find_by(user: customer).id
     )
   end
 
   def name
-    @reservable.title
+    reservable.title
   end
 
   def type
     'event'
   end
-
-  protected
-
-  def tickets_params
-    @other_tickets.map { |ticket| ticket.permit(:event_price_category_id, :booked) }
-  end
 end
diff --git a/app/models/cart_item/event_reservation_ticket.rb b/app/models/cart_item/event_reservation_ticket.rb
new file mode 100644
index 000000000..341e9b16f
--- /dev/null
+++ b/app/models/cart_item/event_reservation_ticket.rb
@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+# A relation table between a pending event reservation and a special price for this event
+class CartItem::EventReservationTicket < ApplicationRecord
+  belongs_to :cart_item_event_reservation, class_name: 'CartItem::EventReservation', inverse_of: :cart_item_event_reservation_tickets
+  belongs_to :event_price_category, inverse_of: :cart_item_event_reservation_tickets
+end
diff --git a/app/models/cart_item/free_extension.rb b/app/models/cart_item/free_extension.rb
index ce4a87d7d..ab2905b4b 100644
--- a/app/models/cart_item/free_extension.rb
+++ b/app/models/cart_item/free_extension.rb
@@ -2,22 +2,20 @@
 
 # A subscription extended for free, added to the shopping cart
 class CartItem::FreeExtension < CartItem::BaseItem
-  def initialize(customer, subscription, new_expiration_date)
-    raise TypeError unless subscription.is_a? Subscription
+  belongs_to :customer_profile, class_name: 'InvoicingProfile'
+  belongs_to :subscription
 
-    @customer = customer
-    @new_expiration_date = new_expiration_date
-    @subscription = subscription
-    super
+  def customer
+    statistic_profile.user
   end
 
   def start_at
-    raise InvalidSubscriptionError if @subscription.nil?
-    if @new_expiration_date.nil? || @new_expiration_date <= @subscription.expired_at
+    raise InvalidSubscriptionError if subscription.nil?
+    if new_expiration_date.nil? || new_expiration_date <= subscription.expired_at
       raise InvalidSubscriptionError, I18n.t('cart_items.must_be_after_expiration')
     end
 
-    @subscription.expired_at
+    subscription.expired_at
   end
 
   def price
@@ -27,14 +25,14 @@ class CartItem::FreeExtension < CartItem::BaseItem
   end
 
   def name
-    I18n.t('cart_items.free_extension', DATE: I18n.l(@new_expiration_date))
+    I18n.t('cart_items.free_extension', DATE: I18n.l(new_expiration_date))
   end
 
   def to_object
     ::OfferDay.new(
-      subscription_id: @subscription.id,
+      subscription_id: subscription.id,
       start_at: start_at,
-      end_at: @new_expiration_date
+      end_at: new_expiration_date
     )
   end
 
diff --git a/app/models/cart_item/machine_reservation.rb b/app/models/cart_item/machine_reservation.rb
index 4c6105ccb..b85d71e15 100644
--- a/app/models/cart_item/machine_reservation.rb
+++ b/app/models/cart_item/machine_reservation.rb
@@ -2,46 +2,40 @@
 
 # A machine reservation added to the shopping cart
 class CartItem::MachineReservation < CartItem::Reservation
-  # @param plan {Plan} a subscription bought at the same time of the reservation OR an already running subscription
-  # @param new_subscription {Boolean} true is new subscription is being bought at the same time of the reservation
-  def initialize(customer, operator, machine, slots, plan: nil, new_subscription: false)
-    raise TypeError unless machine.is_a? Machine
+  self.table_name = 'cart_item_reservations'
 
-    super(customer, operator, machine, slots)
-    @plan = plan
-    @new_subscription = new_subscription
-  end
+  has_many :cart_item_reservation_slots, class_name: 'CartItem::ReservationSlot', dependent: :destroy, inverse_of: :cart_item,
+                                         foreign_key: 'cart_item_id', foreign_type: 'cart_item_type'
+  accepts_nested_attributes_for :cart_item_reservation_slots
 
-  def to_object
-    ::Reservation.new(
-      reservable_id: @reservable.id,
-      reservable_type: Machine.name,
-      slots_reservations_attributes: slots_params,
-      statistic_profile_id: StatisticProfile.find_by(user: @customer).id
-    )
-  end
+  belongs_to :operator_profile, class_name: 'InvoicingProfile'
+  belongs_to :customer_profile, class_name: 'InvoicingProfile'
+
+  belongs_to :reservable, polymorphic: true
+
+  belongs_to :plan
 
   def type
     'machine'
   end
 
   def valid?(all_items)
-    @slots.each do |slot|
+    cart_item_reservation_slots.each do |slot|
       same_hour_slots = SlotsReservation.joins(:reservation).where(
-        reservations: { reservable: @reservable },
+        reservations: { reservable: reservable },
         slot_id: slot[:slot_id],
         canceled_at: nil
       ).count
       if same_hour_slots.positive?
-        @errors[:slot] = I18n.t('cart_item_validation.reserved')
+        errors.add(:slot, I18n.t('cart_item_validation.reserved'))
         return false
       end
-      if @reservable.disabled
-        @errors[:reservable] = I18n.t('cart_item_validation.machine')
+      if reservable.disabled
+        errors.add(:reservable, I18n.t('cart_item_validation.machine'))
         return false
       end
-      unless @reservable.reservable
-        @errors[:reservable] = I18n.t('cart_item_validation.reservable')
+      unless reservable.reservable
+        errors.add(:reservable, I18n.t('cart_item_validation.reservable'))
         return false
       end
     end
@@ -52,9 +46,9 @@ class CartItem::MachineReservation < CartItem::Reservation
   protected
 
   def credits
-    return 0 if @plan.nil?
+    return 0 if plan.nil?
 
-    machine_credit = @plan.machine_credits.find { |credit| credit.creditable_id == @reservable.id }
-    credits_hours(machine_credit, new_plan_being_bought: @new_subscription)
+    machine_credit = plan.machine_credits.find { |credit| credit.creditable_id == reservable.id }
+    credits_hours(machine_credit, new_plan_being_bought: new_subscription)
   end
 end
diff --git a/app/models/cart_item/payment_schedule.rb b/app/models/cart_item/payment_schedule.rb
index f26984f14..eb59849d5 100644
--- a/app/models/cart_item/payment_schedule.rb
+++ b/app/models/cart_item/payment_schedule.rb
@@ -1,23 +1,18 @@
 # frozen_string_literal: true
 
 # A payment schedule applied to plan in the shopping cart
-class CartItem::PaymentSchedule
-  attr_reader :requested, :errors
+class CartItem::PaymentSchedule < ApplicationRecord
+  belongs_to :customer_profile, class_name: 'InvoicingProfile'
+  belongs_to :coupon
+  belongs_to :plan
 
-  def initialize(plan, coupon, requested, customer, start_at = nil)
-    raise TypeError unless coupon.is_a? CartItem::Coupon
-
-    @plan = plan
-    @coupon = coupon
-    @requested = requested
-    @customer = customer
-    @start_at = start_at
-    @errors = {}
+  def customer
+    customer_profile.user
   end
 
   def schedule(total, total_without_coupon)
-    schedule = if @requested && @plan&.monthly_payment
-                 PaymentScheduleService.new.compute(@plan, total_without_coupon, @customer, coupon: @coupon.coupon, start_at: @start_at)
+    schedule = if requested && plan&.monthly_payment
+                 PaymentScheduleService.new.compute(plan, total_without_coupon, customer, coupon: coupon.coupon, start_at: start_at)
                else
                  nil
                end
@@ -36,10 +31,10 @@ class CartItem::PaymentSchedule
   end
 
   def valid?(_all_items)
-    return true unless @requested && @plan&.monthly_payment
+    return true unless requested && plan&.monthly_payment
 
-    if @plan&.disabled
-      @errors[:item] = I18n.t('cart_item_validation.plan')
+    if plan&.disabled
+      errors.add(:plan, I18n.t('cart_item_validation.plan'))
       return false
     end
     true
diff --git a/app/models/cart_item/prepaid_pack.rb b/app/models/cart_item/prepaid_pack.rb
index aa2e89b98..8e1053435 100644
--- a/app/models/cart_item/prepaid_pack.rb
+++ b/app/models/cart_item/prepaid_pack.rb
@@ -2,18 +2,14 @@
 
 # A prepaid-pack added to the shopping cart
 class CartItem::PrepaidPack < CartItem::BaseItem
-  def initialize(pack, customer)
-    raise TypeError unless pack.is_a? PrepaidPack
+  belongs_to :prepaid_pack
 
-    @pack = pack
-    @customer = customer
-    super
+  def customer
+    customer_profile.user
   end
 
   def pack
-    raise InvalidGroupError if @pack.group_id != @customer.group_id
-
-    @pack
+    prepaid_pack
   end
 
   def price
@@ -24,13 +20,13 @@ class CartItem::PrepaidPack < CartItem::BaseItem
   end
 
   def name
-    "#{@pack.minutes / 60} h"
+    "#{pack.minutes / 60} h"
   end
 
   def to_object
     ::StatisticProfilePrepaidPack.new(
-      prepaid_pack_id: @pack.id,
-      statistic_profile_id: StatisticProfile.find_by(user: @customer).id
+      prepaid_pack_id: pack.id,
+      statistic_profile_id: StatisticProfile.find_by(user: customer).id
     )
   end
 
@@ -39,10 +35,14 @@ class CartItem::PrepaidPack < CartItem::BaseItem
   end
 
   def valid?(_all_items)
-    if @pack.disabled
+    if pack.disabled
       @errors[:item] = I18n.t('cart_item_validation.pack')
       return false
     end
+    if pack.group_id != customer.group_id
+      @errors[:group] = "pack is reserved for members of group #{pack.group.name}"
+      return false
+    end
     true
   end
 end
diff --git a/app/models/cart_item/reservation.rb b/app/models/cart_item/reservation.rb
index 364bcf59a..7e792a1ee 100644
--- a/app/models/cart_item/reservation.rb
+++ b/app/models/cart_item/reservation.rb
@@ -7,17 +7,27 @@ GET_SLOT_PRICE_DEFAULT_OPTS = { has_credits: false, elements: nil, is_division:
 
 # A generic reservation added to the shopping cart
 class CartItem::Reservation < CartItem::BaseItem
-  def initialize(customer, operator, reservable, slots)
-    @customer = customer
-    @operator = operator
-    @reservable = reservable
-    @slots = slots.map { |s| expand_slot(s) }
-    super
+  self.abstract_class = true
+
+  def reservable
+    nil
+  end
+
+  def plan
+    nil
+  end
+
+  def operator
+    operator_profile.user
+  end
+
+  def customer
+    customer_profile.user
   end
 
   def price
-    is_privileged = @operator.privileged? && @operator.id != @customer.id
-    prepaid = { minutes: PrepaidPackService.minutes_available(@customer, @reservable) }
+    is_privileged = operator.privileged? && operator.id != customer.id
+    prepaid = { minutes: PrepaidPackService.minutes_available(customer, reservable) }
 
     raise InvalidGroupError, I18n.t('cart_items.group_subscription_mismatch') if !@plan.nil? && @customer.group_id != @plan.group_id
 
@@ -39,7 +49,7 @@ class CartItem::Reservation < CartItem::BaseItem
   end
 
   def name
-    @reservable.name
+    reservable&.name
   end
 
   def valid?(all_items)
@@ -48,39 +58,48 @@ class CartItem::Reservation < CartItem::BaseItem
     reservation_deadline_minutes = Setting.get('reservation_deadline').to_i
     reservation_deadline = reservation_deadline_minutes.minutes.since
 
-    @slots.each do |slot|
-      slot_db = Slot.find(slot[:slot_id])
-      if slot_db.nil?
-        @errors[:slot] = I18n.t('cart_item_validation.slot')
+    cart_item_reservation_slots.each do |sr|
+      slot = sr.slot
+      if slot.nil?
+        errors.add(:slot, I18n.t('cart_item_validation.slot'))
         return false
       end
 
-      availability = Availability.find_by(id: slot[:slot_attributes][:availability_id])
+      availability = slot.availability
       if availability.nil?
-        @errors[:availability] = I18n.t('cart_item_validation.availability')
+        errors.add(:availability, I18n.t('cart_item_validation.availability'))
         return false
       end
 
-      if slot_db.full?
-        @errors[:slot] = I18n.t('cart_item_validation.full')
+      if slot.full?
+        errors.add(:slot, I18n.t('cart_item_validation.full')
         return false
       end
 
-      if slot_db.start_at < reservation_deadline && !@operator.privileged?
-        @errors[:slot] = I18n.t('cart_item_validation.deadline', { MINUTES: reservation_deadline_minutes })
+      if slot.start_at < reservation_deadline && !operator.privileged?
+        errors.add(:slot, I18n.t('cart_item_validation.deadline', { MINUTES: reservation_deadline_minutes }))
         return false
       end
 
       next if availability.plan_ids.empty?
       next if required_subscription?(availability, pending_subscription)
 
-      @errors[:availability] = I18n.t('cart_item_validation.restricted')
+      errors.add(:availability, I18n.t('cart_item_validation.restricted'))
       return false
     end
 
     true
   end
 
+  def to_object
+    ::Reservation.new(
+      reservable_id: reservable_id,
+      reservable_type: reservable_type,
+      slots_reservations_attributes: slots_params,
+      statistic_profile_id: StatisticProfile.find_by(user: customer).id
+    )
+  end
+
   protected
 
   def credits
@@ -91,13 +110,9 @@ class CartItem::Reservation < CartItem::BaseItem
   # Group the slots by date, if the extended_prices_in_same_day option is set to true
   ##
   def grouped_slots
-    return { all: @slots } unless Setting.get('extended_prices_in_same_day')
+    return { all: cart_item_reservation_slots } unless Setting.get('extended_prices_in_same_day')
 
-    @slots.group_by { |slot| slot[:slot_attributes][:start_at].to_date }
-  end
-
-  def expand_slot(slot)
-    slot.merge({ slot_attributes: Slot.find(slot[:slot_id]) })
+    cart_item_reservation_slots.group_by { |slot| slot.slot[:start_at].to_date }
   end
 
   ##
@@ -105,16 +120,16 @@ class CartItem::Reservation < CartItem::BaseItem
   # @param prices {{ prices: Array<{price: Price, duration: number}> }} list of prices to use with the current reservation
   # @see get_slot_price
   ##
-  def get_slot_price_from_prices(prices, slot, is_privileged, options = {})
+  def get_slot_price_from_prices(prices, slot_reservation, is_privileged, options = {})
     options = GET_SLOT_PRICE_DEFAULT_OPTS.merge(options)
 
-    slot_minutes = (slot[:slot_attributes][:end_at].to_time - slot[:slot_attributes][:start_at].to_time) / SECONDS_PER_MINUTE
+    slot_minutes = (slot_reservation.slot[:end_at].to_time - slot_reservation.slot[:start_at].to_time) / SECONDS_PER_MINUTE
     price = prices[:prices].find { |p| p[:duration] <= slot_minutes && p[:duration].positive? }
     price = prices[:prices].first if price.nil?
     hourly_rate = ((Rational(price[:price].amount.to_f) / Rational(price[:price].duration)) * Rational(MINUTES_PER_HOUR)).to_f
 
     # apply the base price to the real slot duration
-    real_price = get_slot_price(hourly_rate, slot, is_privileged, options)
+    real_price = get_slot_price(hourly_rate, slot_reservation, is_privileged, options)
 
     price[:duration] -= slot_minutes
 
@@ -125,7 +140,7 @@ class CartItem::Reservation < CartItem::BaseItem
   # Compute the price of a single slot, according to the base price and the ability for an admin
   # to offer the slot.
   # @param hourly_rate {Number} base price of a slot
-  # @param slot {Hash} Slot object
+  # @param slot_reservation {CartItem::ReservationSlot}
   # @param is_privileged {Boolean} true if the current user has a privileged role (admin or manager)
   # @param [options] {Hash} optional parameters, allowing the following options:
   #  - elements {Array} if provided the resulting price will be append into elements.slots
@@ -134,11 +149,11 @@ class CartItem::Reservation < CartItem::BaseItem
   #  - prepaid_minutes {Number} number of remaining prepaid minutes for the customer
   # @return {Number} price of the slot
   ##
-  def get_slot_price(hourly_rate, slot, is_privileged, options = {})
+  def get_slot_price(hourly_rate, slot_reservation, is_privileged, options = {})
     options = GET_SLOT_PRICE_DEFAULT_OPTS.merge(options)
 
-    slot_rate = options[:has_credits] || (slot[:offered] && is_privileged) ? 0 : hourly_rate
-    slot_minutes = (slot[:slot_attributes][:end_at].to_time - slot[:slot_attributes][:start_at].to_time) / SECONDS_PER_MINUTE
+    slot_rate = options[:has_credits] || (slot_reservation[:offered] && is_privileged) ? 0 : hourly_rate
+    slot_minutes = (slot_reservation.slot[:end_at].to_time - slot_reservation.slot[:start_at].to_time) / SECONDS_PER_MINUTE
     # apply the base price to the real slot duration
     real_price = if options[:is_division]
                    ((Rational(slot_rate) / Rational(MINUTES_PER_HOUR)) * Rational(slot_minutes)).to_f
@@ -155,7 +170,7 @@ class CartItem::Reservation < CartItem::BaseItem
 
     unless options[:elements].nil?
       options[:elements][:slots].push(
-        start_at: slot[:slot_attributes][:start_at],
+        start_at: slot_reservation.slot[:start_at],
         price: real_price,
         promo: (slot_rate != hourly_rate)
       )
@@ -168,19 +183,19 @@ class CartItem::Reservation < CartItem::BaseItem
   # Eg. If the reservation is for 12 hours, and there are prices for 3 hours, 7 hours,
   # and the base price (1 hours), we use the 7 hours price, then 3 hours price, and finally the base price twice (7+3+1+1 = 12).
   # All these prices are returned to be applied to the reservation.
-  def applicable_prices(slots)
-    total_duration = slots.map do |slot|
-      (slot[:slot_attributes][:end_at].to_time - slot[:slot_attributes][:start_at].to_time) / SECONDS_PER_MINUTE
+  def applicable_prices(slots_reservations)
+    total_duration = slots_reservations.map do |slot|
+      (slot.slot[:end_at].to_time - slot.slot[:start_at].to_time) / SECONDS_PER_MINUTE
     end.reduce(:+)
     rates = { prices: [] }
 
     remaining_duration = total_duration
     while remaining_duration.positive?
-      max_duration = @reservable.prices.where(group_id: @customer.group_id, plan_id: @plan.try(:id))
-                                .where(Price.arel_table[:duration].lteq(remaining_duration))
-                                .maximum(:duration)
+      max_duration = reservable&.prices&.where(group_id: customer.group_id, plan_id: plan.try(:id))
+                       &.where(Price.arel_table[:duration].lteq(remaining_duration))
+                       &.maximum(:duration)
       max_duration = 60 if max_duration.nil?
-      max_duration_price = @reservable.prices.find_by(group_id: @customer.group_id, plan_id: @plan.try(:id), duration: max_duration)
+      max_duration_price = reservable&.prices&.find_by(group_id: customer.group_id, plan_id: plan.try(:id), duration: max_duration)
 
       current_duration = [remaining_duration, max_duration].min
       rates[:prices].push(price: max_duration_price, duration: current_duration)
@@ -200,14 +215,14 @@ class CartItem::Reservation < CartItem::BaseItem
 
     hours_available = credits.hours
     unless new_plan_being_bought
-      user_credit = @customer.users_credits.find_by(credit_id: credits.id)
+      user_credit = customer.users_credits.find_by(credit_id: credits.id)
       hours_available = credits.hours - user_credit.hours_used if user_credit
     end
     hours_available
   end
 
   def slots_params
-    @slots.map { |slot| slot.permit(:id, :slot_id, :offered) }
+    cart_item_reservation_slots.map { |sr| { id: sr.slots_reservation_id, slot_id: sr.slot_id, offered: sr.offered } }
   end
 
   ##
@@ -215,9 +230,9 @@ class CartItem::Reservation < CartItem::BaseItem
   # has the required susbcription, otherwise, check if the operator is privileged
   ##
   def required_subscription?(availability, pending_subscription)
-    (@customer.subscribed_plan && availability.plan_ids.include?(@customer.subscribed_plan.id)) ||
+    (customer.subscribed_plan && availability.plan_ids.include?(customer.subscribed_plan.id)) ||
       (pending_subscription && availability.plan_ids.include?(pending_subscription.plan.id)) ||
-      (@operator.manager? && @customer.id != @operator.id) ||
-      @operator.admin?
+      (operator.manager? && customer.id != operator.id) ||
+      operator.admin?
   end
 end
diff --git a/app/models/cart_item/reservation_slot.rb b/app/models/cart_item/reservation_slot.rb
new file mode 100644
index 000000000..9f2db25a4
--- /dev/null
+++ b/app/models/cart_item/reservation_slot.rb
@@ -0,0 +1,9 @@
+# frozen_string_literal: true
+
+# A relation table between a pending reservation and a slot
+class CartItem::ReservationSlot < ApplicationRecord
+  belongs_to :cart_item, polymorphic: true
+
+  belongs_to :slot
+  belongs_to :slots_reservation
+end
diff --git a/app/models/cart_item/space_reservation.rb b/app/models/cart_item/space_reservation.rb
index 7a70dc08b..145c84289 100644
--- a/app/models/cart_item/space_reservation.rb
+++ b/app/models/cart_item/space_reservation.rb
@@ -2,33 +2,26 @@
 
 # A space reservation added to the shopping cart
 class CartItem::SpaceReservation < CartItem::Reservation
-  # @param plan {Plan} a subscription bought at the same time of the reservation OR an already running subscription
-  # @param new_subscription {Boolean} true is new subscription is being bought at the same time of the reservation
-  def initialize(customer, operator, space, slots, plan: nil, new_subscription: false)
-    raise TypeError unless space.is_a? Space
+  self.table_name = 'cart_item_reservations'
 
-    super(customer, operator, space, slots)
-    @plan = plan
-    @space = space
-    @new_subscription = new_subscription
-  end
+  has_many :cart_item_reservation_slots, class_name: 'CartItem::ReservationSlot', dependent: :destroy, inverse_of: :cart_item,
+                                         foreign_key: 'cart_item_id', foreign_type: 'cart_item_type'
+  accepts_nested_attributes_for :cart_item_reservation_slots
 
-  def to_object
-    ::Reservation.new(
-      reservable_id: @reservable.id,
-      reservable_type: Space.name,
-      slots_reservations_attributes: slots_params,
-      statistic_profile_id: StatisticProfile.find_by(user: @customer).id
-    )
-  end
+  belongs_to :operator_profile, class_name: 'InvoicingProfile'
+  belongs_to :customer_profile, class_name: 'InvoicingProfile'
+
+  belongs_to :reservable, polymorphic: true
+
+  belongs_to :plan
 
   def type
     'space'
   end
 
   def valid?(all_items)
-    if @space.disabled
-      @errors[:reservable] = I18n.t('cart_item_validation.space')
+    if reservable.disabled
+      errors.add(:reservable, I18n.t('cart_item_validation.space'))
       return false
     end
 
@@ -38,9 +31,9 @@ class CartItem::SpaceReservation < CartItem::Reservation
   protected
 
   def credits
-    return 0 if @plan.nil?
+    return 0 if plan.nil?
 
-    space_credit = @plan.space_credits.find { |credit| credit.creditable_id == @reservable.id }
-    credits_hours(space_credit, new_plan_being_bought: @new_subscription)
+    space_credit = plan.space_credits.find { |credit| credit.creditable_id == reservable.id }
+    credits_hours(space_credit, new_plan_being_bought: new_subscription)
   end
 end
diff --git a/app/models/cart_item/subscription.rb b/app/models/cart_item/subscription.rb
index f4cd52cb1..e816452b7 100644
--- a/app/models/cart_item/subscription.rb
+++ b/app/models/cart_item/subscription.rb
@@ -2,21 +2,11 @@
 
 # A subscription added to the shopping cart
 class CartItem::Subscription < CartItem::BaseItem
-  attr_reader :start_at
+  belongs_to :plan
+  belongs_to :customer_profile, class_name: 'InvoicingProfile'
 
-  def initialize(plan, customer, start_at = nil)
-    raise TypeError unless plan.is_a? Plan
-
-    @plan = plan
-    @customer = customer
-    @start_at = start_at
-    super
-  end
-
-  def plan
-    raise InvalidGroupError if @plan.group_id != @customer.group_id
-
-    @plan
+  def customer
+    customer_profile.user
   end
 
   def price
@@ -27,14 +17,14 @@ class CartItem::Subscription < CartItem::BaseItem
   end
 
   def name
-    @plan.base_name
+    plan.base_name
   end
 
   def to_object
     ::Subscription.new(
-      plan_id: @plan.id,
-      statistic_profile_id: StatisticProfile.find_by(user: @customer).id,
-      start_at: @start_at
+      plan_id: plan.id,
+      statistic_profile_id: StatisticProfile.find_by(user: customer).id,
+      start_at: start_at
     )
   end
 
@@ -43,8 +33,12 @@ class CartItem::Subscription < CartItem::BaseItem
   end
 
   def valid?(_all_items)
-    if @plan.disabled
-      @errors[:item] = I18n.t('cart_item_validation.plan')
+    if plan.disabled
+      errors.add(:plan, I18n.t('cart_item_validation.plan'))
+      return false
+    end
+    if plan.group_id != customer.group_id
+      errors.add(:group, "plan is reserved for members of group #{plan.group.name}")
       return false
     end
     true
diff --git a/app/models/cart_item/training_reservation.rb b/app/models/cart_item/training_reservation.rb
index bfdc3b528..3edfe6bdf 100644
--- a/app/models/cart_item/training_reservation.rb
+++ b/app/models/cart_item/training_reservation.rb
@@ -2,45 +2,39 @@
 
 # A training reservation added to the shopping cart
 class CartItem::TrainingReservation < CartItem::Reservation
-  # @param plan {Plan} a subscription bought at the same time of the reservation OR an already running subscription
-  # @param new_subscription {Boolean} true is new subscription is being bought at the same time of the reservation
-  def initialize(customer, operator, training, slots, plan: nil, new_subscription: false)
-    raise TypeError unless training.is_a? Training
+  self.table_name = 'cart_item_reservations'
 
-    super(customer, operator, training, slots)
-    @plan = plan
-    @new_subscription = new_subscription
-  end
+  has_many :cart_item_reservation_slots, class_name: 'CartItem::ReservationSlot', dependent: :destroy, inverse_of: :cart_item,
+                                         foreign_key: 'cart_item_id', foreign_type: 'cart_item_type'
+  accepts_nested_attributes_for :cart_item_reservation_slots
+
+  belongs_to :operator_profile, class_name: 'InvoicingProfile'
+  belongs_to :customer_profile, class_name: 'InvoicingProfile'
+
+  belongs_to :reservable, polymorphic: true
+
+  belongs_to :plan
 
   def price
-    base_amount = @reservable.amount_by_group(@customer.group_id).amount
-    is_privileged = @operator.admin? || (@operator.manager? && @operator.id != @customer.id)
+    base_amount = reservable&.amount_by_group(customer.group_id)&.amount
+    is_privileged = operator.admin? || (operator.manager? && operator.id != customer.id)
 
     elements = { slots: [] }
     amount = 0
 
     hours_available = credits
-    @slots.each do |slot|
+    cart_item_reservation_slots.each do |sr|
       amount += get_slot_price(base_amount,
-                               slot,
+                               sr,
                                is_privileged,
                                elements: elements,
-                               has_credits: (@customer.training_credits.size < hours_available),
+                               has_credits: (customer.training_credits.size < hours_available),
                                is_division: false)
     end
 
     { elements: elements, amount: amount }
   end
 
-  def to_object
-    ::Reservation.new(
-      reservable_id: @reservable.id,
-      reservable_type: Training.name,
-      slots_reservations_attributes: slots_params,
-      statistic_profile_id: StatisticProfile.find_by(user: @customer).id
-    )
-  end
-
   def type
     'training'
   end
@@ -48,9 +42,9 @@ class CartItem::TrainingReservation < CartItem::Reservation
   protected
 
   def credits
-    return 0 if @plan.nil?
+    return 0 if plan.nil?
 
-    is_creditable = @plan.training_credits.select { |credit| credit.creditable_id == @reservable.id }.any?
-    is_creditable ? @plan.training_credit_nb : 0
+    is_creditable = plan&.training_credits&.select { |credit| credit.creditable_id == reservable&.id }&.any?
+    is_creditable ? plan&.training_credit_nb : 0
   end
 end
diff --git a/app/models/coupon.rb b/app/models/coupon.rb
index 20051d990..9195d1a9c 100644
--- a/app/models/coupon.rb
+++ b/app/models/coupon.rb
@@ -2,16 +2,18 @@
 
 # Coupon is a textual code associated with a discount rate or an amount of discount
 class Coupon < ApplicationRecord
-  has_many :invoices, dependent: :nullify
-  has_many :payment_schedule, dependent: :nullify
-  has_many :orders, dependent: :nullify
+  has_many :invoices, dependent: :restrict_with_error
+  has_many :payment_schedule, dependent: :restrict_with_error
+  has_many :orders, dependent: :restrict_with_error
+
+  has_many :cart_item_coupons, class_name: 'CartItem::Coupon', dependent: :destroy
 
   after_create :create_gateway_coupon
   before_destroy :delete_gateway_coupon
 
   validates :name, presence: true
   validates :code, presence: true
-  validates :code, format: { with: /\A[A-Z0-9\-]+\z/, message: I18n.t('coupon.invalid_format') }
+  validates :code, format: { with: /\A[A-Z0-9\-]+\z/, message: I18n.t('coupon.code_format_error') }
   validates :code, uniqueness: true
   validates :validity_per_user, presence: true
   validates :validity_per_user, inclusion: { in: %w[once forever] }
diff --git a/app/models/event.rb b/app/models/event.rb
index cfaa0fdce..330dc8bac 100644
--- a/app/models/event.rb
+++ b/app/models/event.rb
@@ -31,6 +31,8 @@ class Event < ApplicationRecord
   has_one :advanced_accounting, as: :accountable, dependent: :destroy
   accepts_nested_attributes_for :advanced_accounting, allow_destroy: true
 
+  has_many :cart_item_event_reservations, class_name: 'CartItem::EventReservation', dependent: :destroy
+
   attr_accessor :recurrence, :recurrence_end_at
 
   before_save :update_nb_free_places
diff --git a/app/models/event_price_category.rb b/app/models/event_price_category.rb
index 47b6e8558..8fe8e8858 100644
--- a/app/models/event_price_category.rb
+++ b/app/models/event_price_category.rb
@@ -5,7 +5,8 @@ class EventPriceCategory < ApplicationRecord
   belongs_to :event
   belongs_to :price_category
 
-  has_many :tickets
+  has_many :tickets, dependent: :restrict_with_error
+  has_many :cart_item_event_reservation_tickets, class_name: 'CartItem::EventReservationTicket', dependent: :restrict_with_error
 
   validates :price_category_id, presence: true
   validates :amount, presence: true
@@ -17,5 +18,4 @@ class EventPriceCategory < ApplicationRecord
   def verify_no_associated_tickets
     throw(:abort) unless tickets.count.zero?
   end
-
 end
diff --git a/app/models/invoicing_profile.rb b/app/models/invoicing_profile.rb
index 6e9cd012f..78678ca8b 100644
--- a/app/models/invoicing_profile.rb
+++ b/app/models/invoicing_profile.rb
@@ -27,6 +27,25 @@ class InvoicingProfile < ApplicationRecord
 
   has_many :accounting_lines, dependent: :destroy
 
+  # as operator
+  has_many :operated_cart_item_event_reservations, class_name: 'CartItem::EventReservation', dependent: :nullify, inverse_of: :operator_profile
+  has_many :operated_cart_item_machine_reservations, class_name: 'CartItem::MachineReservation', dependent: :nullify,
+                                                     inverse_of: :operator_profile
+  has_many :operated_cart_item_space_reservations, class_name: 'CartItem::SpaceReservation', dependent: :nullify, inverse_of: :operator_profile
+  has_many :operated_cart_item_training_reservations, class_name: 'CartItem::TrainingReservation', dependent: :nullify,
+                                                      inverse_of: :operator_profile
+  has_many :operated_cart_item_coupon, class_name: 'CartItem::Coupon', dependent: :nullify, inverse_of: :operator_profile
+  # as customer
+  has_many :cart_item_event_reservations, class_name: 'CartItem::EventReservation', dependent: :destroy, inverse_of: :customer_profile
+  has_many :cart_item_machine_reservations, class_name: 'CartItem::MachineReservation', dependent: :destroy, inverse_of: :customer_profile
+  has_many :cart_item_space_reservations, class_name: 'CartItem::SpaceReservation', dependent: :destroy, inverse_of: :customer_profile
+  has_many :cart_item_training_reservations, class_name: 'CartItem::TrainingReservation', dependent: :destroy, inverse_of: :customer_profile
+  has_many :cart_item_free_extensions, class_name: 'CartItem::FreeExtension', dependent: :destroy, inverse_of: :customer_profile
+  has_many :cart_item_subscriptions, class_name: 'CartItem::Subscription', dependent: :destroy, inverse_of: :customer_profile
+  has_many :cart_item_prepaid_packs, class_name: 'CartItem::PrepaidPack', dependent: :destroy, inverse_of: :customer_profile
+  has_many :cart_item_coupons, class_name: 'CartItem::Coupon', dependent: :destroy, inverse_of: :customer_profile
+  has_many :cart_item_payment_schedules, class_name: 'CartItem::PaymentSchedule', dependent: :destroy, inverse_of: :customer_profile
+
   before_validation :set_external_id_nil
   validates :external_id, uniqueness: true, allow_blank: true
   validates :address, presence: true, if: -> { Setting.get('address_required') }
diff --git a/app/models/machine.rb b/app/models/machine.rb
index 57a5c929e..72d100e10 100644
--- a/app/models/machine.rb
+++ b/app/models/machine.rb
@@ -37,6 +37,9 @@ class Machine < ApplicationRecord
   has_one :advanced_accounting, as: :accountable, dependent: :destroy
   accepts_nested_attributes_for :advanced_accounting, allow_destroy: true
 
+  has_many :cart_item_machine_reservations, class_name: 'CartItem::MachineReservation', dependent: :destroy, inverse_of: :reservable,
+                                            foreign_type: 'reservable_type', foreign_key: 'reservable_id'
+
   belongs_to :category
 
   after_create :create_statistic_subtype
diff --git a/app/models/order.rb b/app/models/order.rb
index 311aa096c..037e69a70 100644
--- a/app/models/order.rb
+++ b/app/models/order.rb
@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-# Order is a model for the user hold information of order
+# Order is a model used to hold orders data
 class Order < PaymentDocument
   belongs_to :statistic_profile
   belongs_to :operator_profile, class_name: 'InvoicingProfile'
diff --git a/app/models/plan.rb b/app/models/plan.rb
index 6c1e393a0..8370551e9 100644
--- a/app/models/plan.rb
+++ b/app/models/plan.rb
@@ -15,6 +15,12 @@ class Plan < ApplicationRecord
   has_many :prices, dependent: :destroy
   has_one :payment_gateway_object, -> { order id: :desc }, inverse_of: :plan, as: :item, dependent: :destroy
 
+  has_many :cart_item_machine_reservations, class_name: 'CartItem::MachineReservation', dependent: :destroy
+  has_many :cart_item_space_reservations, class_name: 'CartItem::SpaceReservation', dependent: :destroy
+  has_many :cart_item_training_reservations, class_name: 'CartItem::TrainingReservation', dependent: :destroy
+  has_many :cart_item_subscriptions, class_name: 'CartItem::Subscription', dependent: :destroy
+  has_many :cart_item_payment_schedules, class_name: 'CartItem::PaymentSchedule', dependent: :destroy
+
   extend FriendlyId
   friendly_id :base_name, use: :slugged
 
diff --git a/app/models/prepaid_pack.rb b/app/models/prepaid_pack.rb
index 76f08aaa8..16d752b36 100644
--- a/app/models/prepaid_pack.rb
+++ b/app/models/prepaid_pack.rb
@@ -8,12 +8,14 @@
 # The number of hours in a pack is stored in minutes.
 class PrepaidPack < ApplicationRecord
   belongs_to :priceable, polymorphic: true
-  belongs_to :machine, foreign_type: 'Machine', foreign_key: 'priceable_id'
-  belongs_to :space, foreign_type: 'Space', foreign_key: 'priceable_id'
+  belongs_to :machine, foreign_type: 'Machine', foreign_key: 'priceable_id', inverse_of: :prepaid_packs
+  belongs_to :space, foreign_type: 'Space', foreign_key: 'priceable_id', inverse_of: :prepaid_packs
 
   belongs_to :group
 
-  has_many :statistic_profile_prepaid_packs
+  has_many :statistic_profile_prepaid_packs, dependent: :destroy
+
+  has_many :cart_item_prepaid_packs, class_name: 'CartItem::PrepaidPack', dependent: :destroy
 
   validates :amount, :group_id, :priceable_id, :priceable_type, :minutes, presence: true
 
diff --git a/app/models/project.rb b/app/models/project.rb
index c0d1b418b..6e0bb3497 100644
--- a/app/models/project.rb
+++ b/app/models/project.rb
@@ -59,7 +59,7 @@ class Project < ApplicationRecord
   scope :published_or_drafts, lambda { |author_profile|
     where("state = 'published' OR (state = 'draft' AND author_statistic_profile_id = ?)", author_profile)
   }
-  scope :user_projects, ->(author_profile) { where(author_statistic_profile: author_profile) }
+  scope :user_projects, ->(author_profile) { where(author_statistic_profile_id: author_profile) }
   scope :collaborations, ->(collaborators_ids) { joins(:project_users).where(project_users: { user_id: collaborators_ids }) }
   scope :with_machine, ->(machines_ids) { joins(:projects_machines).where(projects_machines: { machine_id: machines_ids }) }
   scope :with_theme, ->(themes_ids) { joins(:projects_themes).where(projects_themes: { theme_id: themes_ids }) }
diff --git a/app/models/shopping_cart.rb b/app/models/shopping_cart.rb
index 032477afa..ba3f6378d 100644
--- a/app/models/shopping_cart.rb
+++ b/app/models/shopping_cart.rb
@@ -70,7 +70,7 @@ class ShoppingCart
       payment.post_save(payment_id, payment_type)
     end
 
-    success = !payment.nil? && objects.map(&:errors).flatten.map(&:empty?).all? && items.map(&:errors).map(&:empty?).all?
+    success = !payment.nil? && objects.map(&:errors).flatten.map(&:empty?).all? && items.map(&:errors).map(&:blank?).all?
     errors = objects.map(&:errors).flatten.concat(items.map(&:errors))
     errors.push('Unable to create the PaymentDocument') if payment.nil?
     { success: success, payment: payment, errors: errors }
diff --git a/app/models/slot.rb b/app/models/slot.rb
index f6fc13178..354fb0963 100644
--- a/app/models/slot.rb
+++ b/app/models/slot.rb
@@ -10,6 +10,8 @@ class Slot < ApplicationRecord
   has_many :reservations, through: :slots_reservations
   belongs_to :availability
 
+  has_many :cart_item_reservation_slots, class_name: 'CartItem::ReservationSlot', dependent: :destroy
+
   attr_accessor :is_reserved, :machine, :space, :title, :can_modify, :current_user_slots_reservations_ids
 
   def full?(reservable = nil)
diff --git a/app/models/slots_reservation.rb b/app/models/slots_reservation.rb
index 3594dd14d..ba31cff2e 100644
--- a/app/models/slots_reservation.rb
+++ b/app/models/slots_reservation.rb
@@ -5,6 +5,7 @@
 class SlotsReservation < ApplicationRecord
   belongs_to :slot
   belongs_to :reservation
+  has_one :cart_item_reservation_slot, class_name: 'CartItem::ReservationSlot', dependent: :nullify
 
   after_update :set_ex_start_end_dates_attrs, if: :slot_changed?
   after_update :notify_member_and_admin_slot_is_modified, if: :slot_changed?
@@ -13,7 +14,7 @@ class SlotsReservation < ApplicationRecord
   after_update :update_event_nb_free_places, if: :canceled?
 
   def set_ex_start_end_dates_attrs
-    update_columns(ex_start_at: previous_slot.start_at, ex_end_at: previous_slot.end_at)
+    update_columns(ex_start_at: previous_slot.start_at, ex_end_at: previous_slot.end_at) # rubocop:disable Rails/SkipsModelValidations
   end
 
   private
diff --git a/app/models/space.rb b/app/models/space.rb
index 3921e58c1..399b99d30 100644
--- a/app/models/space.rb
+++ b/app/models/space.rb
@@ -31,6 +31,9 @@ class Space < ApplicationRecord
   has_one :advanced_accounting, as: :accountable, dependent: :destroy
   accepts_nested_attributes_for :advanced_accounting, allow_destroy: true
 
+  has_many :cart_item_space_reservations, class_name: 'CartItem::SpaceReservation', dependent: :destroy, inverse_of: :reservable,
+                                          foreign_type: 'reservable_type', foreign_key: 'reservable_id'
+
   after_create :create_statistic_subtype
   after_create :create_space_prices
   after_create :update_gateway_product
diff --git a/app/models/subscription.rb b/app/models/subscription.rb
index 227110028..3e9ffa370 100644
--- a/app/models/subscription.rb
+++ b/app/models/subscription.rb
@@ -12,6 +12,8 @@ class Subscription < ApplicationRecord
   has_many :invoice_items, as: :object, dependent: :destroy
   has_many :offer_days, dependent: :destroy
 
+  has_many :cart_item_free_extensions, class_name: 'CartItem::FreeExtension', dependent: :destroy
+
   validates :plan_id, presence: true
   validates_with SubscriptionGroupValidator
 
diff --git a/app/models/training.rb b/app/models/training.rb
index 8e853e006..f81999872 100644
--- a/app/models/training.rb
+++ b/app/models/training.rb
@@ -32,6 +32,9 @@ class Training < ApplicationRecord
   has_one :advanced_accounting, as: :accountable, dependent: :destroy
   accepts_nested_attributes_for :advanced_accounting, allow_destroy: true
 
+  has_many :cart_item_training_reservations, class_name: 'CartItem::TrainingReservation', dependent: :destroy, inverse_of: :reservable,
+                                             foreign_type: 'reservable_type', foreign_key: 'reservable_id'
+
   after_create :create_statistic_subtype
   after_create :create_trainings_pricings
   after_create :update_gateway_product
diff --git a/app/services/cart/add_item_service.rb b/app/services/cart/add_item_service.rb
index c0e8bb9fd..6f868d0fd 100644
--- a/app/services/cart/add_item_service.rb
+++ b/app/services/cart/add_item_service.rb
@@ -5,10 +5,30 @@ class Cart::AddItemService
   def call(order, orderable, quantity = 1)
     return order if quantity.to_i.zero?
 
-    raise Cart::InactiveProductError unless orderable.is_active
+    item = case orderable
+           when Product
+             add_product(order, orderable, quantity)
+           when Slot
+             add_slot(order, orderable)
+           else
+             raise Cart::UnknownItemError
+           end
 
     order.created_at = Time.current if order.order_items.length.zero?
 
+    ActiveRecord::Base.transaction do
+      item.save
+      Cart::UpdateTotalService.new.call(order)
+      order.save
+    end
+    order.reload
+  end
+
+  private
+
+  def add_product(order, orderable, quantity)
+    raise Cart::InactiveProductError unless orderable.is_active
+
     item = order.order_items.find_by(orderable: orderable)
     quantity = orderable.quantity_min > quantity.to_i && item.nil? ? orderable.quantity_min : quantity.to_i
 
@@ -19,11 +39,14 @@ class Cart::AddItemService
     end
     raise Cart::OutStockError if item.quantity > orderable.stock['external']
 
-    ActiveRecord::Base.transaction do
-      item.save
-      Cart::UpdateTotalService.new.call(order)
-      order.save
-    end
-    order.reload
+    item
+  end
+
+  def add_slot(order, orderable)
+    item = order.order_items.find_by(orderable: orderable)
+
+    item = order.order_items.new(quantity: 1, orderable: orderable, amount: orderable.amount || 0) if item.nil?
+
+    item
   end
 end
diff --git a/app/services/cart_service.rb b/app/services/cart_service.rb
index 5b15457f6..aea1c834d 100644
--- a/app/services/cart_service.rb
+++ b/app/services/cart_service.rb
@@ -11,25 +11,46 @@ class CartService
   # @see app/frontend/src/javascript/models/payment.ts > interface ShoppingCart
   ##
   def from_hash(cart_items)
+    cart_items.permit! if cart_items.is_a? ActionController::Parameters
+
     @customer = customer(cart_items)
     plan_info = plan(cart_items)
 
     items = []
     cart_items[:items].each do |item|
-      if ['subscription', :subscription].include?(item.keys.first)
-        items.push(CartItem::Subscription.new(plan_info[:plan], @customer, item[:subscription][:start_at])) if plan_info[:new_subscription]
+      if ['subscription', :subscription].include?(item.keys.first) && plan_info[:new_subscription]
+        items.push(CartItem::Subscription.new(
+                     plan: plan_info[:plan],
+                     customer_profile: @customer.invoicing_profile,
+                     start_at: item[:subscription][:start_at]
+                   ))
       elsif ['reservation', :reservation].include?(item.keys.first)
         items.push(reservable_from_hash(item[:reservation], plan_info))
       elsif ['prepaid_pack', :prepaid_pack].include?(item.keys.first)
-        items.push(CartItem::PrepaidPack.new(PrepaidPack.find(item[:prepaid_pack][:id]), @customer))
+        items.push(CartItem::PrepaidPack.new(
+                     prepaid_pack: PrepaidPack.find(item[:prepaid_pack][:id]),
+                     customer_profile: @customer.invoicing_profile
+                   ))
       elsif ['free_extension', :free_extension].include?(item.keys.first)
-        items.push(CartItem::FreeExtension.new(@customer, plan_info[:subscription], item[:free_extension][:end_at]))
+        items.push(CartItem::FreeExtension.new(
+                     customer_profile: @customer.invoicing_profile,
+                     subscription: plan_info[:subscription],
+                     new_expiration_date: item[:free_extension][:end_at]
+                   ))
       end
     end
 
-    coupon = CartItem::Coupon.new(@customer, @operator, cart_items[:coupon_code])
+    coupon = CartItem::Coupon.new(
+      customer_profile: @customer.invoicing_profile,
+      operator_profile: @operator.invoicing_profile,
+      coupon: Coupon.find_by(code: cart_items[:coupon_code])
+    )
     schedule = CartItem::PaymentSchedule.new(
-      plan_info[:plan], coupon, cart_items[:payment_schedule], @customer, plan_info[:subscription]&.start_at
+      plan: plan_info[:plan],
+      coupon: coupon,
+      requested: cart_items[:payment_schedule],
+      customer_profile: @customer.invoicing_profile,
+      start_at: plan_info[:subscription]&.start_at
     )
 
     ShoppingCart.new(
@@ -47,19 +68,40 @@ class CartService
     subscription = payment_schedule.payment_schedule_objects.find { |pso| pso.object_type == Subscription.name }&.subscription
     plan = subscription&.plan
 
-    coupon = CartItem::Coupon.new(@customer, @operator, payment_schedule.coupon&.code)
-    schedule = CartItem::PaymentSchedule.new(plan, coupon, true, @customer, subscription.start_at)
+    coupon = CartItem::Coupon.new(
+      customer_profile: @customer.invoicing_profile,
+      operator_profile: @operator.invoicing_profile,
+      coupon: payment_schedule.coupon
+    )
+    schedule = CartItem::PaymentSchedule.new(
+      plan: plan,
+      coupon: coupon,
+      requested: true,
+      customer_profile: @customer.invoicing_profile,
+      start_at: subscription.start_at
+    )
 
     items = []
     payment_schedule.payment_schedule_objects.each do |object|
       if object.object_type == Subscription.name
-        items.push(CartItem::Subscription.new(object.subscription.plan, @customer, object.subscription.start_at))
+        items.push(CartItem::Subscription.new(
+                     plan: object.subscription.plan,
+                     customer_profile: @customer.invoicing_profile,
+                     start_at: object.subscription.start_at
+                   ))
       elsif object.object_type == Reservation.name
         items.push(reservable_from_payment_schedule_object(object, plan))
       elsif object.object_type == PrepaidPack.name
-        items.push(CartItem::PrepaidPack.new(object.statistic_profile_prepaid_pack.prepaid_pack_id, @customer))
+        items.push(CartItem::PrepaidPack.new(
+                     prepaid_pack_id: object.statistic_profile_prepaid_pack.prepaid_pack_id,
+                     customer_profile: @customer.invoicing_profile
+                   ))
       elsif object.object_type == OfferDay.name
-        items.push(CartItem::FreeExtension.new(@customer, object.offer_day.subscription, object.offer_day.end_date))
+        items.push(CartItem::FreeExtension.new(
+                     customer_profile: @customer.invoicing_profile,
+                     subscription: object.offer_day.subscription,
+                     new_expiration_date: object.offer_day.end_date
+                   ))
       end
     end
 
@@ -83,7 +125,11 @@ class CartService
              if cart_items[:items][index][:subscription][:plan_id]
                new_plan_being_bought = true
                plan = Plan.find(cart_items[:items][index][:subscription][:plan_id])
-               subscription = CartItem::Subscription.new(plan, @customer, cart_items[:items][index][:subscription][:start_at]).to_object
+               subscription = CartItem::Subscription.new(
+                 plan: plan,
+                 customer_profile: @customer.invoicing_profile,
+                 start_at: cart_items[:items][index][:subscription][:start_at]
+               ).to_object
                plan
              end
            elsif @customer.subscribed_plan
@@ -107,31 +153,31 @@ class CartService
     reservable = cart_item[:reservable_type]&.constantize&.find(cart_item[:reservable_id])
     case reservable
     when Machine
-      CartItem::MachineReservation.new(@customer,
-                                       @operator,
-                                       reservable,
-                                       cart_item[:slots_reservations_attributes],
+      CartItem::MachineReservation.new(customer_profile: @customer.invoicing_profile,
+                                       operator_profile: @operator.invoicing_profile,
+                                       reservable: reservable,
+                                       cart_item_reservation_slots_attributes: cart_item[:slots_reservations_attributes],
                                        plan: plan_info[:plan],
                                        new_subscription: plan_info[:new_subscription])
     when Training
-      CartItem::TrainingReservation.new(@customer,
-                                        @operator,
-                                        reservable,
-                                        cart_item[:slots_reservations_attributes],
+      CartItem::TrainingReservation.new(customer_profile: @customer.invoicing_profile,
+                                        operator_profile: @operator.invoicing_profile,
+                                        reservable: reservable,
+                                        cart_item_reservation_slots_attributes: cart_item[:slots_reservations_attributes],
                                         plan: plan_info[:plan],
                                         new_subscription: plan_info[:new_subscription])
     when Event
-      CartItem::EventReservation.new(@customer,
-                                     @operator,
-                                     reservable,
-                                     cart_item[:slots_reservations_attributes],
+      CartItem::EventReservation.new(customer_profile: @customer.invoicing_profile,
+                                     operator_profile: @operator.invoicing_profile,
+                                     event: reservable,
+                                     cart_item_reservation_slots_attributes: cart_item[:slots_reservations_attributes],
                                      normal_tickets: cart_item[:nb_reserve_places],
-                                     other_tickets: cart_item[:tickets_attributes])
+                                     cart_item_event_reservation_tickets_attributes: cart_item[:tickets_attributes] || {})
     when Space
-      CartItem::SpaceReservation.new(@customer,
-                                     @operator,
-                                     reservable,
-                                     cart_item[:slots_reservations_attributes],
+      CartItem::SpaceReservation.new(customer_profile: @customer.invoicing_profile,
+                                     operator_profile: @operator.invoicing_profile,
+                                     reservable: reservable,
+                                     cart_item_reservation_slots_attributes: cart_item[:slots_reservations_attributes],
                                      plan: plan_info[:plan],
                                      new_subscription: plan_info[:new_subscription])
     else
@@ -144,31 +190,31 @@ class CartService
     reservable = object.reservation.reservable
     case reservable
     when Machine
-      CartItem::MachineReservation.new(@customer,
-                                       @operator,
-                                       reservable,
-                                       object.reservation.slots_reservations,
+      CartItem::MachineReservation.new(customer_profile: @customer.invoicing_profile,
+                                       operator_profile: @operator.invoicing_profile,
+                                       reservable: reservable,
+                                       cart_item_reservation_slots_attributes: object.reservation.slots_reservations,
                                        plan: plan,
                                        new_subscription: true)
     when Training
-      CartItem::TrainingReservation.new(@customer,
-                                        @operator,
-                                        reservable,
-                                        object.reservation.slots_reservations,
+      CartItem::TrainingReservation.new(customer_profile: @customer.invoicing_profile,
+                                        operator_profile: @operator.invoicing_profile,
+                                        reservable: reservable,
+                                        cart_item_reservation_slots_attributes: object.reservation.slots_reservations,
                                         plan: plan,
                                         new_subscription: true)
     when Event
-      CartItem::EventReservation.new(@customer,
-                                     @operator,
-                                     reservable,
-                                     object.reservation.slots_reservations,
+      CartItem::EventReservation.new(customer_profile: @customer.invoicing_profile,
+                                     operator_profile: @operator.invoicing_profile,
+                                     event: reservable,
+                                     cart_item_reservation_slots_attributes: object.reservation.slots_reservation,
                                      normal_tickets: object.reservation.nb_reserve_places,
-                                     other_tickets: object.reservation.tickets)
+                                     cart_item_event_reservation_tickets_attributes: object.reservation.tickets)
     when Space
-      CartItem::SpaceReservation.new(@customer,
-                                     @operator,
-                                     reservable,
-                                     object.reservation.slots_reservations,
+      CartItem::SpaceReservation.new(customer_profile: @customer.invoicing_profile,
+                                     operator_profile: @operator.invoicing_profile,
+                                     reservable: reservable,
+                                     cart_item_reservation_slots_attributes: object.reservation.slots_reservations,
                                      plan: plan,
                                      new_subscription: true)
     else
diff --git a/app/validators/stripe_card_token_validator.rb b/app/validators/stripe_card_token_validator.rb
index 89f160e89..a813a6763 100644
--- a/app/validators/stripe_card_token_validator.rb
+++ b/app/validators/stripe_card_token_validator.rb
@@ -7,9 +7,9 @@ class StripeCardTokenValidator
 
     res = Stripe::Token.retrieve(options[:token], api_key: Setting.get('stripe_secret_key'))
     if res[:id] != options[:token]
-      record.errors[:card_token] << "A problem occurred while retrieving the card with the specified token: #{res.id}"
+      record.errors.add(:card_token, "A problem occurred while retrieving the card with the specified token: #{res.id}")
     end
   rescue Stripe::InvalidRequestError => e
-    record.errors[:card_token] << e
+    record.errors.add(:card_token, e)
   end
 end
diff --git a/config/locales/en.yml b/config/locales/en.yml
index 23944812b..83c57c0bc 100644
--- a/config/locales/en.yml
+++ b/config/locales/en.yml
@@ -67,6 +67,8 @@ en:
     length_must_be_slot_multiple: "must be at least %{MIN} minutes after the start date"
     must_be_associated_with_at_least_1_machine: "must be associated with at least 1 machine"
     deleted_user: "Deleted user"
+  coupon:
+    code_format_error: "only caps letters, numbers, and dashes are allowed"
   #members management
   members:
     unable_to_change_the_group_while_a_subscription_is_running: "Unable to change the group while a subscription is running"
diff --git a/db/migrate/20221228152719_create_cart_item_event_reservation.rb b/db/migrate/20221228152719_create_cart_item_event_reservation.rb
new file mode 100644
index 000000000..41f72060f
--- /dev/null
+++ b/db/migrate/20221228152719_create_cart_item_event_reservation.rb
@@ -0,0 +1,15 @@
+# frozen_string_literal: true
+
+# From this migration, we save the pending event reservations in database, instead of just creating them on the fly
+class CreateCartItemEventReservation < ActiveRecord::Migration[5.2]
+  def change
+    create_table :cart_item_event_reservations do |t|
+      t.integer :normal_tickets
+      t.references :event, foreign_key: true
+      t.references :operator_profile, foreign_key: { to_table: 'invoicing_profiles' }
+      t.references :customer_profile, foreign_key: { to_table: 'invoicing_profiles' }
+
+      t.timestamps
+    end
+  end
+end
diff --git a/db/migrate/20221228152747_create_cart_item_event_reservation_ticket.rb b/db/migrate/20221228152747_create_cart_item_event_reservation_ticket.rb
new file mode 100644
index 000000000..177ddb475
--- /dev/null
+++ b/db/migrate/20221228152747_create_cart_item_event_reservation_ticket.rb
@@ -0,0 +1,14 @@
+# frozen_string_literal: true
+
+# A relation table between a pending event reservation and a special price for this event
+class CreateCartItemEventReservationTicket < ActiveRecord::Migration[5.2]
+  def change
+    create_table :cart_item_event_reservation_tickets do |t|
+      t.integer :booked
+      t.references :event_price_category, foreign_key: true, index: { name: 'index_cart_item_tickets_on_event_price_category' }
+      t.references :cart_item_event_reservation, foreign_key: true, index: { name: 'index_cart_item_tickets_on_cart_item_event_reservation' }
+
+      t.timestamps
+    end
+  end
+end
diff --git a/db/migrate/20221228160449_create_cart_item_reservation_slot.rb b/db/migrate/20221228160449_create_cart_item_reservation_slot.rb
new file mode 100644
index 000000000..3266e9750
--- /dev/null
+++ b/db/migrate/20221228160449_create_cart_item_reservation_slot.rb
@@ -0,0 +1,15 @@
+# frozen_string_literal: true
+
+# A relation table between a pending reservation and a slot
+class CreateCartItemReservationSlot < ActiveRecord::Migration[5.2]
+  def change
+    create_table :cart_item_reservation_slots do |t|
+      t.references :cart_item, polymorphic: true, index: { name: 'index_cart_item_slots_on_cart_item' }
+      t.references :slot, foreign_key: true
+      t.references :slots_reservation, foreign_key: true
+      t.boolean :offered, default: false
+
+      t.timestamps
+    end
+  end
+end
diff --git a/db/migrate/20221229085430_create_cart_item_reservation.rb b/db/migrate/20221229085430_create_cart_item_reservation.rb
new file mode 100644
index 000000000..7500eb26c
--- /dev/null
+++ b/db/migrate/20221229085430_create_cart_item_reservation.rb
@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+# From this migration, we save the pending machine/space/training reservations in database, instead of just creating them on the fly
+class CreateCartItemReservation < ActiveRecord::Migration[5.2]
+  def change
+    create_table :cart_item_reservations do |t|
+      t.references :reservable, polymorphic: true, index: { name: 'index_cart_item_reservations_on_reservable' }
+      t.references :plan, foreign_key: true
+      t.boolean :new_subscription
+      t.references :customer_profile, foreign_key: { to_table: 'invoicing_profiles' }
+      t.references :operator_profile, foreign_key: { to_table: 'invoicing_profiles' }
+      t.string :type
+
+      t.timestamps
+    end
+  end
+end
diff --git a/db/migrate/20221229094334_create_cart_item_free_extension.rb b/db/migrate/20221229094334_create_cart_item_free_extension.rb
new file mode 100644
index 000000000..e21e18979
--- /dev/null
+++ b/db/migrate/20221229094334_create_cart_item_free_extension.rb
@@ -0,0 +1,14 @@
+# frozen_string_literal: true
+
+# From this migration, we save the pending free-extensions of subscriptions in database, instead of just creating them on the fly
+class CreateCartItemFreeExtension < ActiveRecord::Migration[5.2]
+  def change
+    create_table :cart_item_free_extensions do |t|
+      t.references :subscription, foreign_key: true
+      t.datetime :new_expiration_date
+      t.references :customer_profile, foreign_key: { to_table: 'invoicing_profiles' }
+
+      t.timestamps
+    end
+  end
+end
diff --git a/db/migrate/20221229100157_create_cart_item_subscription.rb b/db/migrate/20221229100157_create_cart_item_subscription.rb
new file mode 100644
index 000000000..81b4ca343
--- /dev/null
+++ b/db/migrate/20221229100157_create_cart_item_subscription.rb
@@ -0,0 +1,14 @@
+# frozen_string_literal: true
+
+# From this migration, we save the pending subscriptions in database, instead of just creating them on the fly
+class CreateCartItemSubscription < ActiveRecord::Migration[5.2]
+  def change
+    create_table :cart_item_subscriptions do |t|
+      t.references :plan, foreign_key: true
+      t.datetime :start_at
+      t.references :customer_profile, foreign_key: { to_table: 'invoicing_profiles' }
+
+      t.timestamps
+    end
+  end
+end
diff --git a/db/migrate/20221229103407_create_cart_item_prepaid_pack.rb b/db/migrate/20221229103407_create_cart_item_prepaid_pack.rb
new file mode 100644
index 000000000..1df8f95c1
--- /dev/null
+++ b/db/migrate/20221229103407_create_cart_item_prepaid_pack.rb
@@ -0,0 +1,13 @@
+# frozen_string_literal: true
+
+# From this migration, we save the pending prepaid-packs in database, instead of just creating them on the fly
+class CreateCartItemPrepaidPack < ActiveRecord::Migration[5.2]
+  def change
+    create_table :cart_item_prepaid_packs do |t|
+      t.references :prepaid_pack, foreign_key: true
+      t.references :customer_profile, foreign_key: { to_table: 'invoicing_profiles' }
+
+      t.timestamps
+    end
+  end
+end
diff --git a/db/migrate/20221229105954_add_unique_index_on_coupon_code.rb b/db/migrate/20221229105954_add_unique_index_on_coupon_code.rb
new file mode 100644
index 000000000..8238ea244
--- /dev/null
+++ b/db/migrate/20221229105954_add_unique_index_on_coupon_code.rb
@@ -0,0 +1,8 @@
+# frozen_string_literal: true
+
+# Coupon's codes should validate uniqness in database
+class AddUniqueIndexOnCouponCode < ActiveRecord::Migration[5.2]
+  def change
+    add_index :coupons, :code, unique: true
+  end
+end
diff --git a/db/migrate/20221229115757_create_cart_item_coupon.rb b/db/migrate/20221229115757_create_cart_item_coupon.rb
new file mode 100644
index 000000000..28c3f338f
--- /dev/null
+++ b/db/migrate/20221229115757_create_cart_item_coupon.rb
@@ -0,0 +1,14 @@
+# frozen_string_literal: true
+
+# From this migration, we save the pending coupons in database, instead of just creating them on the fly
+class CreateCartItemCoupon < ActiveRecord::Migration[5.2]
+  def change
+    create_table :cart_item_coupons do |t|
+      t.references :coupon, foreign_key: true
+      t.references :customer_profile, foreign_key: { to_table: 'invoicing_profiles' }
+      t.references :operator_profile, foreign_key: { to_table: 'invoicing_profiles' }
+
+      t.timestamps
+    end
+  end
+end
diff --git a/db/migrate/20221229120932_create_cart_item_payment_schedule.rb b/db/migrate/20221229120932_create_cart_item_payment_schedule.rb
new file mode 100644
index 000000000..b75b37756
--- /dev/null
+++ b/db/migrate/20221229120932_create_cart_item_payment_schedule.rb
@@ -0,0 +1,16 @@
+# frozen_string_literal: true
+
+# From this migration, we save the pending payment schedules in database, instead of just creating them on the fly
+class CreateCartItemPaymentSchedule < ActiveRecord::Migration[5.2]
+  def change
+    create_table :cart_item_payment_schedules do |t|
+      t.references :plan, foreign_key: true
+      t.references :coupon, foreign_key: true
+      t.boolean :requested
+      t.datetime :start_at
+      t.references :customer_profile, foreign_key: { to_table: 'invoicing_profiles' }
+
+      t.timestamps
+    end
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
index 4ba30590d..4ed4819f2 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -19,8 +19,8 @@ ActiveRecord::Schema.define(version: 2023_01_31_104958) do
   enable_extension "unaccent"
 
   create_table "abuses", id: :serial, force: :cascade do |t|
-    t.integer "signaled_id"
     t.string "signaled_type"
+    t.integer "signaled_id"
     t.string "first_name"
     t.string "last_name"
     t.string "email"
@@ -68,8 +68,8 @@ ActiveRecord::Schema.define(version: 2023_01_31_104958) do
     t.string "locality"
     t.string "country"
     t.string "postal_code"
-    t.integer "placeable_id"
     t.string "placeable_type"
+    t.integer "placeable_id"
     t.datetime "created_at"
     t.datetime "updated_at"
   end
@@ -93,8 +93,8 @@ ActiveRecord::Schema.define(version: 2023_01_31_104958) do
   end
 
   create_table "assets", id: :serial, force: :cascade do |t|
-    t.integer "viewable_id"
     t.string "viewable_type"
+    t.integer "viewable_id"
     t.string "attachment"
     t.string "type"
     t.datetime "created_at"
@@ -281,8 +281,8 @@ ActiveRecord::Schema.define(version: 2023_01_31_104958) do
   end
 
   create_table "credits", id: :serial, force: :cascade do |t|
-    t.integer "creditable_id"
     t.string "creditable_type"
+    t.integer "creditable_id"
     t.integer "plan_id"
     t.integer "hours"
     t.datetime "created_at"
@@ -524,15 +524,15 @@ ActiveRecord::Schema.define(version: 2023_01_31_104958) do
 
   create_table "notifications", id: :serial, force: :cascade do |t|
     t.integer "receiver_id"
-    t.integer "attached_object_id"
     t.string "attached_object_type"
+    t.integer "attached_object_id"
     t.integer "notification_type_id"
     t.boolean "is_read", default: false
     t.datetime "created_at"
     t.datetime "updated_at"
     t.string "receiver_type"
     t.boolean "is_send", default: false
-    t.jsonb "meta_data", default: {}
+    t.jsonb "meta_data", default: "{}"
     t.index ["notification_type_id"], name: "index_notifications_on_notification_type_id"
     t.index ["receiver_id"], name: "index_notifications_on_receiver_id"
   end
@@ -772,8 +772,8 @@ ActiveRecord::Schema.define(version: 2023_01_31_104958) do
   create_table "prices", id: :serial, force: :cascade do |t|
     t.integer "group_id"
     t.integer "plan_id"
-    t.integer "priceable_id"
     t.string "priceable_type"
+    t.integer "priceable_id"
     t.integer "amount"
     t.datetime "created_at", null: false
     t.datetime "updated_at", null: false
@@ -976,8 +976,8 @@ ActiveRecord::Schema.define(version: 2023_01_31_104958) do
     t.text "message"
     t.datetime "created_at"
     t.datetime "updated_at"
-    t.integer "reservable_id"
     t.string "reservable_type"
+    t.integer "reservable_id"
     t.integer "nb_reserve_places"
     t.integer "statistic_profile_id"
     t.index ["reservable_type", "reservable_id"], name: "index_reservations_on_reservable_type_and_reservable_id"
@@ -986,8 +986,8 @@ ActiveRecord::Schema.define(version: 2023_01_31_104958) do
 
   create_table "roles", id: :serial, force: :cascade do |t|
     t.string "name"
-    t.integer "resource_id"
     t.string "resource_type"
+    t.integer "resource_id"
     t.datetime "created_at"
     t.datetime "updated_at"
     t.index ["name", "resource_type", "resource_id"], name: "index_roles_on_name_and_resource_type_and_resource_id"
diff --git a/test/integration/subscriptions/create_as_user_test.rb b/test/integration/subscriptions/create_as_user_test.rb
index b947be596..cb449eeb3 100644
--- a/test/integration/subscriptions/create_as_user_test.rb
+++ b/test/integration/subscriptions/create_as_user_test.rb
@@ -2,6 +2,8 @@
 
 require 'test_helper'
 
+module Subscriptions; end
+
 class Subscriptions::CreateAsUserTest < ActionDispatch::IntegrationTest
   setup do
     @user = User.find_by(username: 'jdupond')
@@ -57,7 +59,7 @@ class Subscriptions::CreateAsUserTest < ActionDispatch::IntegrationTest
 
     # Check notifications were sent for every admins
     notifications = Notification.where(
-      notification_type_id: NotificationType.find_by_name('notify_admin_subscribed_plan'),
+      notification_type_id: NotificationType.find_by_name('notify_admin_subscribed_plan'), # rubocop:disable Rails/DynamicFindBy
       attached_object_type: 'Subscription',
       attached_object_id: subscription[:id]
     )
@@ -100,7 +102,7 @@ class Subscriptions::CreateAsUserTest < ActionDispatch::IntegrationTest
     assert_equal Mime[:json], response.content_type
 
     # Check the error was handled
-    assert_match(/plan is not compatible/, response.body)
+    assert_match(/plan is reserved for members of group/, response.body)
 
     # Check that the user has no subscription
     assert_nil @user.subscription, "user's subscription was found"
@@ -162,7 +164,7 @@ class Subscriptions::CreateAsUserTest < ActionDispatch::IntegrationTest
 
     # Check notifications were sent for every admins
     notifications = Notification.where(
-      notification_type_id: NotificationType.find_by_name('notify_admin_subscribed_plan'),
+      notification_type_id: NotificationType.find_by_name('notify_admin_subscribed_plan'), # rubocop:disable Rails/DynamicFindBy
       attached_object_type: 'Subscription',
       attached_object_id: subscription[:id]
     )
diff --git a/test/integration/subscriptions/renew_as_user_test.rb b/test/integration/subscriptions/renew_as_user_test.rb
index 40b13059f..3b505ec00 100644
--- a/test/integration/subscriptions/renew_as_user_test.rb
+++ b/test/integration/subscriptions/renew_as_user_test.rb
@@ -2,6 +2,8 @@
 
 require 'test_helper'
 
+module Subscriptions; end
+
 class Subscriptions::RenewAsUserTest < ActionDispatch::IntegrationTest
   setup do
     @user = User.find_by(username: 'atiermoulin')
@@ -60,7 +62,7 @@ class Subscriptions::RenewAsUserTest < ActionDispatch::IntegrationTest
 
     # Check notifications were sent for every admins
     notifications = Notification.where(
-      notification_type_id: NotificationType.find_by_name('notify_admin_subscribed_plan'),
+      notification_type_id: NotificationType.find_by_name('notify_admin_subscribed_plan'), # rubocop:disable Rails/DynamicFindBy
       attached_object_type: 'Subscription',
       attached_object_id: subscription[:id]
     )