Validate ModelState.IsValid globally for all controllers

Question

In my ASP.NET Core Controllers I always check if the ModelState is valid:

[HttpPost("[action]")]
public async Task<IActionResult> DoStuff([FromBody]DoStuffRequest request)
{
  if (!ModelState.IsValid)
  {
    return BadRequest("invalid parameters");
  }
  else
  {
    return Ok("some data"));
  }
}

Is there a way to check validity of the ModelState globally using a filter so I don't have to do this in every API item in every controller again? It would be nice if the action could rely on the modelstate being valid and not needing to check:

[HttpPost("[action]")]
public async Task<IActionResult> DoStuff([FromBody]DoStuffRequest request)
{
  return Ok("some data"));
}

Answer 1

For ASP.NET Core 2.0, to avoid applying attributes to all Controllers or Actions individually;

Define a filter:

namespace Test
{
    public sealed class ModelStateCheckFilter : IActionFilter
    {
        public void OnActionExecuted(ActionExecutedContext context) { }

        public void OnActionExecuting(ActionExecutingContext context)
        {
            if (!context.ModelState.IsValid)
            {
                context.Result = new BadRequestObjectResult(context.ModelState);
            }
        }
    }
}

Then in your Startup.cs, add it as filter:

    public void ConfigureServices(IServiceCollection services)
    {
        services.AddMvc(config =>
        {
            config.Filters.Add(new ModelStateCheckFilter());
        });
    }