Skip to main content

ValidationBehavior

Namespace: RA.Utilities.Dispatcher.Behaviors

ValidationBehavior is a pipeline behavior that runs all registered FluentValidation validators against the incoming request before the handler executes. Invalid requests never reach your business logic — the behavior short-circuits the pipeline and returns a failed result.

📦 Type Definition​

public class ValidationBehavior<TRequest, TResponse> : IPipelineBehavior<TRequest, TResponse>
    where TRequest : IRequest<TResponse>
{
    public ValidationBehavior(IEnumerable<IValidator<TRequest>> validators);
}

public class ValidationBehavior<TRequest> : IPipelineBehavior<TRequest>
    where TRequest : IRequest
{
    public ValidationBehavior(IEnumerable<IValidator<TRequest>> validators);
}

🎯 How It Works​

  1. The behavior resolves all registered IValidator<TRequest> implementations (empty collection when none are registered).
  2. It runs them through ValidationUtilities.ValidateAsync(...) — the same asynchronous validation path used across RA.Utilities.
  3. If validation passes, it calls next() and returns the inner result unchanged.
  4. If validation fails, it returns Result.Failure(...) containing a BadRequestException built from the collected ValidationFailure entries (via ValidationUtilities.CreateValidationErrorResult). Map that failed result to a 400 Bad Request at the call site.

🚀 Usage​

.AddValidator<TValidator>() registers the validator and wires this behavior into the pipeline in one call:

public class CreateProductCommandValidator : AbstractValidator<CreateProductCommand>
{
    public CreateProductCommandValidator()
    {
        RuleFor(x => x.Name).NotEmpty().MaximumLength(100);
        RuleFor(x => x.Price).GreaterThan(0);
    }
}

builder.Services
    .AddDispatcher<CreateProductCommand, int, CreateProductHandler>()
    .AddValidator<CreateProductCommandValidator>(); // registers validator + ValidationBehavior

Handling the failure at the call site:

Result<int> result = await dispatcher.Send(command);
if (result.IsFailure)
    return Results.BadRequest(result.Exception.Message); // BadRequestException with structured errors

🧠 Notes​

  • Multiple validators for the same request are all executed.
  • To register a validator without the behavior, use AddTransient<IValidator<TRequest>, TValidator>() directly.