Description:
This is the final and most critical step for multi-user support. Authentication alone is not enough; we must ensure that a user's data (their products, sales, etc.) is completely invisible and inaccessible to other users.
Tasks (Backend):
Entity Relationships: Add a @ManyToOne relationship to the User entity in all primary business entities: Product, Sale, Customer, Expense, Category, Provider.
Service Layer Refactoring: Modify all service methods (findAll, findById, create, update, delete) to always include a filter for the currently authenticated user's ID. The user can be retrieved from the SecurityContextHolder.
Example: productRepository.findByIdAndUserId(productId, userId).
When creating a new resource (e.g., createProduct), the authenticated User must be associated with it before saving.
Database Update: Ensure the database schema is updated (via ddl-auto: update in dev or a migration script) to add the new user_id foreign key columns.
Acceptance Criteria:
Test Scenario:
User A registers and logs in.
User A creates 3 products and 1 customer.
User A logs out.
User B registers and logs in.
User B navigates to the products page. They must see 0 products.
User B navigates to the customers page. They must see 0 customers.
An attempt by User A to directly access a resource owned by User B via the API (if the ID is known) must result in a 404 Not Found.
Description:
This is the final and most critical step for multi-user support. Authentication alone is not enough; we must ensure that a user's data (their products, sales, etc.) is completely invisible and inaccessible to other users.
Tasks (Backend):
Acceptance Criteria:
Test Scenario: