Introduction
A Controller.HandleUnknownAction
method gets called when a controller cannot find an action method that matches a browser request.
Background
In this article, I will explore handling unknown actions. A Controller.HandleUnknownAction
method gets called when a controller cannot find an action method that matches a browser request. I have implemented the following method in my previous article: Implementing HTTP File Upload with ASP.NET MVC.
Here is the syntax in C#:
protected virtual void HandleUnknownAction(string actionName)
Here is a FileUploadController
class that implements HandleUnknownAction
as shown below:
[HandleError]
public class FileUploadController : Controller
{
public ActionResult FileUpload()
{
return View();
}
[AcceptVerbs(HttpVerbs.Post)]
public ActionResult FileUpload(HttpPostedFileBase uploadFile)
{
if (uploadFile.ContentLength > 0)
{
string filePath =
Path.Combine(HttpContext.Server.MapPath("../Uploads"),
Path.GetFileName(uploadFile.FileName));
uploadFile.SaveAs(filePath);
}
return View();
}
protected override void HandleUnknownAction(string actionName)
{
actionName = "FileUpload";
this.View(actionName).ExecuteResult(this.ControllerContext);
}
}
The above example displays the FileUpload
view when a request for the FileUpload
action is made on the controller. If there is no matching view, then the FileUpload
controller HandleUnknownAction()
method is invoked. I have hard coded the FileUpload
view so that if the browser request does not match the FileUpload
, it will explicitly call the FileUpload
action. Here is the view with the unknown action:
Notice that the controller does not have the UploadToGoogle
action, but our HandleUnknownAction()
method is invoked and it explicitly calls the FileUpload
action.
Summary
A Controller.HandleUnknownAction
method gets called when a controller cannot find an action method that matches a browser request. Therefore, in your controller class, you don’t need to explicitly code an action method for each view.
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