snippet from somewhere. An ActionFilter for return the corrent Html Repsonse Code for an invalid model state in ASP.NET WebApi

ValidateModelStateAttribute.cs

using System;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Web.Http.Controllers;
using System.Web.Http.Filters;

[AttributeUsage(AttributeTargets.Class | AttributeTargets.Method, AllowMultiple = false, Inherited = true)]
public class ValidateModelStateAttribute : ActionFilterAttribute
{
    public override void OnActionExecuting(HttpActionContext actionContext)
    {
        var modelState = actionContext.ModelState;

        if (!modelState.IsValid)
            actionContext.Response = actionContext.Request.CreateErrorResponse(HttpStatusCode.BadRequest, modelState);
        //else if (IsFormBodyNull(actionContext))
        //    actionContext.Response = actionContext.Request.CreateErrorResponse(HttpStatusCode.BadRequest, "Request has no body content");
    }

    private bool IsFormBodyNull(HttpActionContext actionContext)
    {
        return actionContext.ActionDescriptor.GetParameters()
            .Where(x => x.ParameterBinderAttribute != null && actionContext.ActionArguments[x.ParameterName] == null)
            .FirstOrDefault() != null;
    }
}