I am working on an e-shop using Strapi as the backend and Next.js as the frontend. I encountered an issue where, if multiple users add products to their basket simultaneously (simulated using two different browsers), a race condition occurs. The user who loses the race ends up with an empty basket.

Current Implementation:

1. Fetching Products:
   I retrieve the product collection from Strapi to display all products on the webpage:

   {
     "kind": "collectionType",
     "collectionName": "products",
     "info": {
       "singularName": "product",
       "pluralName": "products",
       "displayName": "Product"
     },
     "attributes": {
       "title": { "type": "string", "required": true },
       "price": { "type": "decimal", "required": true },
       "user_cart": { "type": "relation", "relation": "manyToOne", "target": "api::user-cart.user-cart", "inversedBy": "product" }
     }
   }
   

2. Adding Product to User Cart:

   {
     "kind": "collectionType",
     "collectionName": "user_carts",
     "info": {
       "singularName": "user-cart",
       "pluralName": "user-carts",
       "displayName": "User Cart"
     },
     "attributes": {
       "product": { "type": "relation", "relation": "oneToMany", "target": "api::product.product", "mappedBy": "user_cart" }
     }
   }
   

Problem:

When I check the user who lost the race, their product array is empty, while the winning user gets the relation data correctly.

Why am I not receiving the related product information (e.g., product title) for the losing user?