Web Api Required Parameter

Question

Using ASP.NET Web API. Is there a way to automatically return a status code 400 if a parameter is null? I found this question but that is a global solution that is applied

Answer 1

The accepted solution takes it upon itself to report back any errors. A more appropriate approach for MVC5 is to let the controller handle (via model validation) the reporting of any errors, aka something like this:

using System.ComponentModel.DataAnnotations;
using System.Linq;
using System.Web.Http.Controllers;
using System.Web.Http.Filters;
using System.Web.Http.ModelBinding;

[AttributeUsage(AttributeTargets.Class | AttributeTargets.Method, AllowMultiple = true)]
public sealed class ValidateParametersAttribute : ActionFilterAttribute
{
    public override void OnActionExecuting(HttpActionContext context)
    {
        var descriptor = context.ActionDescriptor;
        if (descriptor != null)
        {
            var modelState = context.ModelState;
            foreach (var parameterDescriptor in descriptor.GetParameters())
            {
                EvaluateValidationAttributes(
                    suppliedValue: context.ActionArguments[parameterDescriptor.ParameterName],
                    modelState: modelState,
                    parameterDescriptor: parameterDescriptor
                );
            }
        }

        base.OnActionExecuting(context);
    }

    static private void EvaluateValidationAttributes(HttpParameterDescriptor parameterDescriptor, object suppliedValue, ModelStateDictionary modelState)
    {
        var parameterName = parameterDescriptor.ParameterName;

        parameterDescriptor
            .GetCustomAttributes