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FluentValidation

The Spur.FluentValidation package bridges FluentValidation validators with Spur pipelines, converting validation failures into structured Error values.

Installation​

dotnet add package Spur.FluentValidation

Standalone usage​

Run a validator and get a Result<T> back:

using Spur.FluentValidation;

public class CreateUserValidator : AbstractValidator<CreateUserRequest>
{
    public CreateUserValidator()
    {
        RuleFor(x => x.Email).NotEmpty().EmailAddress();
        RuleFor(x => x.Name).NotEmpty().MaximumLength(100);
    }
}

var validator = new CreateUserValidator();
var result = validator.ValidateToResult(request);

if (result.IsFailure)
{
    // result.Error contains structured validation details
}

Async​

var result = await validator.ValidateToResultAsync(request);

Pipeline integration​

Plug FluentValidation directly into a Spur pipeline:

public async Task<Result<UserDto>> CreateUser(CreateUserRequest request)
{
    return await Result.Start(request)
        .Validate(_validator)                 // FluentValidation runs here
        .ThenAsync(r => _repo.CreateAsync(r))
        .Map(user => user.ToDto());
}

Async pipeline​

return await Result.Start(request)
    .ValidateAsync(_validator, cancellationToken)
    .ThenAsync(r => _repo.CreateAsync(r));

From Task<Result<T>>​

return await GetRequestAsync()
    .ValidateAsync(_validator, cancellationToken)
    .ThenAsync(ProcessAsync);

Error format​

When validation fails, the error has:

  • Code: "VALIDATION_ERROR"
  • Message: "One or more validation errors occurred."
  • HttpStatus: 422
  • Category: ErrorCategory.Validation
  • Extensions: contains a structured errors dictionary with property names and their messages:
{
  "errorCode": "VALIDATION_ERROR",
  "status": 422,
  "detail": "One or more validation errors occurred.",
  "errors": {
    "Email": ["'Email' must not be empty.", "'Email' is not a valid email address."],
    "Name": ["'Name' must not be empty."]
  }
}

See also​