Overview

Creates a new Publisher entity in the Catalog domain. Publishers are aggregate roots that represent book publishing companies within our bounded context.

This endpoint follows Domain-Driven Design principles by implementing the Command pattern through MediatR. The command is validated using FluentValidation before being processed by the domain service.

Implementation Details

The Create Publisher operation is implemented using the CQRS pattern with a dedicated command handler:

Key Components

1. CreatePublisherCommand: Implements ICommand<Guid> to create a new publisher
2. CreatePublisherHandler: Processes the command using repository pattern
3. CreatePublisherValidator: Validates the command parameters using FluentValidation
4. CreatePublisherEndpoint: Maps the HTTP POST request to the command handler
5. Publisher Entity: Domain entity that encapsulates publisher data and business rules
6. PublisherCreatedEvent: Domain event raised when publisher is created

Domain Context

In our domain model, Publisher represents a core aggregate that encapsulates:

• Unique identifier (Id)
• Name of the publishing company
• Associated metadata and business rules

The Create Publisher command is a write operation that:

1. Validates the input parameters
2. Creates a new Publisher entity
3. Registers a PublisherCreatedEvent domain event
4. Persists the entity to the repository
5. Returns the unique identifier of the created publisher

Business Rules

• Name must be provided and cannot be empty
• Name must not exceed the maximum length limit
• The operation raises a domain event that can trigger side effects in other bounded contexts

Technical Implementation

The implementation uses several patterns and techniques:

1. CQRS: Separates the write model (command) from the read model (query)
2. Repository Pattern: The IPublisherRepository abstracts the data access layer
3. Domain-Driven Design: Uses domain entities and events to encapsulate business logic
4. Minimal API: Uses .NET’s minimal API approach with endpoint mapping
5. FluentValidation: Validates the command parameters

The command execution flow:

1. The endpoint receives the HTTP POST request with the publisher data
2. The validator ensures all business rules are satisfied
3. The command handler creates a new Publisher entity
4. The entity registers a domain event
5. The repository persists the entity and publishes domain events
6. The endpoint returns a 201 Created response with the publisher ID and location header

Authorization

This endpoint requires admin privileges. Users must have the Admin role to access this endpoint.

Architecture

POST (/api/v1/publishers)

Request Body

Example Usage

curl -X POST https://api.bookworm.com/api/v1/publisers \
  -H "Authorization: Bearer <admin-token>" \
  -H "Content-Type: application/json" \
  -d '{
    "name": "New Publisher"
  }'

Validation Rules

• Name field is required and cannot be empty
• Name must not exceed the large data schema length limit

Responses

201 Created

Returns the newly created publisher’s ID (GUID) with the following:

• Response Body: GUID of the created publisher
• Location Header: URL to the newly created publisher resource following the pattern /api/v1/publishers/{id}

400 Bad Request

Returned when:

• The request body fails validation rules
• The name field is missing or empty
• The name exceeds the maximum length limit

401 Unauthorized

Returned when the request lacks valid authentication credentials.

403 Forbidden

Returned when the authenticated user lacks admin privileges.