EndpointBuilderExtensions

Namespace: RA.Utilities.Api.Extensions

The EndpointBuilderExtensions class is designed to improve the developer experience when applying validation to Minimal API endpoints. It provides a more fluent and readable syntax for adding the ValidationEndpointFilter.

Instead of the more verbose AddEndpointFilter<ValidationEndpointFilter<TModel>>, this class provides a simple and elegant shortcut.

Validate<TModel>()

This extension method for RouteHandlerBuilder adds an endpoint filter that automatically validates a model of type TModel using FluentValidation. If validation fails, the request is short-circuited, and a standardized validation error is returned before the endpoint handler is ever executed.

On failure, the filter returns an HTTP 400 Bad Request with a structured JSON body containing the validation errors, providing a consistent and predictable error-handling experience for your API consumers.

{
  "responseCode": 400,
  "responseType": "BadRequest",
  "responseMessage": "One or more validation errors occurred.",
  "result": [
    {
      "propertyName": "Email",
      "errorMessage": "'Email' must not be empty.",
      "attemptedValue": "",
      "errorCode": "NotEmptyValidator"
    }
  ]
}

🚀 Usage

By chaining the Validate<TModel>() method to your endpoint definition, you can make your code more concise and readable.

Consider the following example where we want to validate a CreateProductRequest model.

Before

Without the extension, you would need to add the filter manually:

app.MapPost("/products", (CreateProductRequest request) => { ... })
   .AddEndpointFilter<ValidationEndpointFilter<CreateProductRequest>>();

After

With the Validate<TModel>() extension method, the same registration becomes much cleaner:

app.MapPost("/products", (CreateProductRequest request) => { ... })
   .Validate<CreateProductRequest>();