Overview

This endpoint retrieves a user’s shopping basket based on their identity. In our domain model, a Basket is an aggregate root that contains a collection of BasketItems, each representing a book the user intends to purchase.

Implementation Details

The Get Basket operation is implemented using the CQRS pattern with a dedicated query handler and post-processor:

Key Components

1. GetBasketQuery: Implements IQuery<CustomerBasketDto> to retrieve a user’s basket
2. GetBasketHandler: Processes the query using repository pattern
3. PostGetBasketHandler: Post-processor that enriches basket items with book details from the Catalog service
4. BookService: gRPC client for the Catalog service
5. CustomerBasketDto: Data transfer object representing the basket and its items

Technical Implementation

The query execution follows these steps:

1. Authentication: Extracts the user ID from the JWT token claims
2. Basket Retrieval: Fetches the basket from Redis using the user ID as the key
3. DTO Conversion: Converts the domain entity to a DTO
4. Data Enrichment: Post-processes the DTO to add book details from the Catalog service
5. Response: Returns the enriched basket DTO to the client

The implementation includes several notable features:

• Cross-Service Data Enrichment: Basket items are enriched with book details from the Catalog service
• gRPC Communication: Uses gRPC for efficient inter-service communication
• Post-Processing: Uses MediatR’s post-processing pipeline for separation of concerns
• Error Handling: Specific exceptions for different error scenarios

Domain Context

Within our bounded context, the basket represents the current selection of items a user has chosen but not yet purchased. The basket is identified by a unique user identifier and maintains the state of the user’s shopping session.

Business Rules

• Each user can have only one active basket
• Basket items contain references to catalog items (books) with quantity
• Prices are stored in the basket to maintain price consistency during the shopping session
• Anonymous users’ baskets are tracked via temporary identifiers
• The basket is automatically populated with current book information from the catalog service

Use Cases

• Initial page load for returning users
• Checkout process initiation
• Basket summary display
• Price verification before checkout

Integration Points

This endpoint is consumed by the web UI and integrates with the Catalog service to fetch current book information.

Architecture

GET (/api/v1/baskets)

Request Body

No request body is required. The basket ID is automatically determined from the authenticated user’s identity.

Example Usage

curl -X GET "https:///api.bookworm.com/api/v1/baskets" \
  -H "Authorization: Bearer <your-jwt-token>" \
  -H "Content-Type: application/json" \

Responses

200 OK

Returns the user’s basket details, including items and their prices. The response includes the basket ID and a list of items with their quantities and prices.

Example Response:

{
  "id": "0195e531-cc9d-7925-ba84-b9588bb3653d",
  "items": [
    {
      "id": "0195e531-cc9d-71f1-ad7f-57cfc0712f1b",
      "quantity": 2,
      "name": "The Great Gatsby",
      "price": 29.99,
      "priceSale": 24.99
    }
  ]
}

401 Unauthorized

The user is not authenticated. The request must include a valid authentication token.

404 Not Found

The basket for the authenticated user was not found.

Error Handling

The endpoint handles the following error scenarios:

• Missing or invalid authentication token
• Basket not found for the user
• Book information not found in the catalog service
• Invalid request parameters

Security

• Requires authentication via Bearer token
• User can only access their own basket
• All requests must be made over HTTPS

Rate Limiting

• Standard rate limits apply
• Maximum 100 requests per minute per user

Caching

• Response is not cached
• Each request fetches fresh data from the catalog service