3. Core Technology Requirements

1. Entity Relationships

   One-to-many / many-to-many relationship between entities. Operations:

   • Retrieving all child entities for a given parent.
   • Creating, updating and deleting child entities associated with a parent.
   • Implementing a cascading delete.

2. Use of Date and Time Objects

   Handling date-related data.

   • Accept and validate date inputs.
   • Using a consistent format.
   • An endpoint that filters by date range / sorts results based on date fields.

3. Incorporating DTOs (Data Transfer Objects)

   Use DTOs to control data exchanged between the client and server.

   • Separation of concerns by decoupling the internal data model from the API response format.
   • Clean and minimal responses that expose only the required data fields.

4. Error Handling and Validation

   Implement structured and meaningful error handling.

   • Validating client input.
   • Appropriate HTTP status codes and error messages.
   • Clear, consistent error responses.

   Examples:

   • Example: @Positive on price ensures inventory values are realistic.
   • Example: @PastOrPresent on manufacture dates prevents future entries.
     Jakarta Validation is used at the DTO level.

5. Pagination The API supports pagination for endpoints returning collections.

6. Validation Error (400): Triggered by invalid inputs like negative prices.

7. Resource Not Found (404): Triggered when a model name does not exist in the database.