How to skip action execution from an ActionFilter?

Question

Is it possible to skip the whole action method execution and return a specific ActionResult when a certain condition is met in OnActionExecuting?

Answer 1

If anyone is extending ActionFilterAttribute in MVC 5 API, then you must be getting HttpActionContext instead of ActionExecutingContext as the type of parameter. In that case, simply set httpActionContext.Response to new HttpResponseMessage and you are good to go.

I was making a validation filter and here is how it looks like:

    /// 

    /// Occurs before the action method is invoked.
    /// This will validate the request
    /// 
    /// The http action context.
    public override void OnActionExecuting(HttpActionContext actionContext)
    {
        ApiController ctrl = (actionContext.ControllerContext.Controller as ApiController);
        if (!ctrl.ModelState.IsValid)
        {
            var s = ctrl.ModelState.Select(t => new { Field = t.Key, Errors = t.Value.Errors.Select(e => e.ErrorMessage) });
            actionContext.Response = new System.Net.Http.HttpResponseMessage()
            {
                Content = new StringContent(JsonConvert.SerializeObject(s)),
                ReasonPhrase = "Validation error",
                StatusCode = (System.Net.HttpStatusCode)422
            };
        }
    }