Use custom validation responses with fluent validation

Question

Hello I am trying to get custom validation response for my webApi using .NET Core.

Here I want to have response model like

[{
  ErrorCode:
  ErrorFi         


        

Answer 1

try with this:

services.Configure(options =>
{
    options.SuppressModelStateInvalidFilter = true;
});

I validate the model with fluentvalidation, after build the BadResquest response in a ActionFilter class:

public class ValidateModelStateAttribute : ActionFilterAttribute
{
    public override void OnActionExecuting(ActionExecutingContext context)
    {
        if (!context.ModelState.IsValid)
        {
            var errors = context.ModelState.Values.Where(v => v.Errors.Count > 0)
                    .SelectMany(v => v.Errors)
                    .Select(v => v.ErrorMessage)
                    .ToList();

            var responseObj = new
            {
                Message = "Bad Request",
                Errors = errors                    
            };

            context.Result = new JsonResult(responseObj)
            {
                StatusCode = 400
            };
        }
    }
}

In StartUp.cs:

        services.AddMvc(options =>
        {
            options.Filters.Add(typeof(ValidateModelStateAttribute));
        })
        .AddFluentValidation(fvc => fvc.RegisterValidatorsFromAssemblyContaining());

        services.Configure(options =>
        {
            options.SuppressModelStateInvalidFilter = true;
        });

And it works fine. I hope you find it useful