Throw an error if null is passed to action. ASP.NET Core

NullValidationFilter.cs

using System;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.Filters;

namespace Example
{
    public class NullValidationFilter : Attribute, IActionFilter
    {
        public void OnActionExecuting(ActionExecutingContext context)
        {
            foreach (var k in context.ActionArguments.Keys) {
                object o; 
                context.ActionArguments.TryGetValue(k, out o);
                if (o == null) {
                    context.Result = new BadRequestResult();
                }
            }
        }

        public void OnActionExecuted(ActionExecutedContext context) {}
    }
}

NullValidationFilter2.cs

using System;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.Filters;

namespace Example
{
    public class NullValidationFilter : Attribute, IActionFilter
    {
        public void OnActionExecuting(ActionExecutingContext context)
        {
            if (context.ActionArguments.Values.Contains(null)) {
                context.Result = new BadRequestResult();
            }
        }

        public void OnActionExecuted(ActionExecutedContext context) {}
    }
}

I hereby place this to public domain.