Action Filters in ASP.Net MVC framework

How to use an Action filter?

1. Create a ASP.NET MVC application, by selection File->New->Project->Web
2. Right click on Controller folder and add one controller. Feel free to give any name. Here name is TestController.
3. Create an Action inside the controller. Feel free to give any name of the Action. Here name is TestingActionFilter()
4.TestingActionFilter() action is returning current time as string.
5. Apply Action filter OutputCache on the Action.
6. Give required parameter for OutputCache action filter.

{codecitation class="brush: csharp; gutter: true;" width="650px"}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;
using System.Web.Mvc.Ajax;

namespace usingActionFilter.Controllers
{
public class TestController : Controller
{

[OutputCache(Duration = 5,VaryByParam="none")]
public string TestingActionFilter()
{
return DateTime.Now.ToString();
}

}
}

{/codecitation}

7. Run the application.
8. Type http://localhost:1903/Test/TestingActionFilter to get the output. Port number may differ in your case.

Action filter class
1. The base class of all Action filter are ActionFilterAttribute class.
2. This is under namespace System.Web.Mvc
3. It extends FilterAttribute Class.
4. Class contains four methods , which is shown below

{codecitation class="brush: csharp; gutter: true;" width="650px"}

using System;

namespace System.Web.Mvc
{

[AttributeUsage(AttributeTargets.Class | AttributeTargets.Method, Inherited = true, AllowMultiple = false)]
public abstract class ActionFilterAttribute : FilterAttribute, IActionFilter, IResultFilter
{
protected ActionFilterAttribute();


public virtual void OnActionExecuted(ActionExecutedContext filterContext);

public virtual void OnActionExecuting(ActionExecutingContext filterContext);

public virtual void OnResultExecuted(ResultExecutedContext filterContext);

public virtual void OnResultExecuting(ResultExecutingContext filterContext);
}
}


{/codecitation}

Creating a Custom Action Filter

1. Add a class in MVC project. Feel free to give any name.

2. Extend the class ActionFilterAttribute
3. Override the methods. Call method Message in all overridden function.



{codecitation class="brush: csharp; gutter: true;" width="700px"}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;
using System.Web.Routing;
using System.Diagnostics;

namespace usingActionFilter
{
public class CustomActionFilter : ActionFilterAttribute
{
public override void OnActionExecuted(ActionExecutedContext filterContext)
{
//base.OnActionExecuted(filterContext);

Message(filterContext.RouteData);
}
public override void OnActionExecuting(ActionExecutingContext filterContext)
{
// base.OnActionExecuting(filterContext);
Message(filterContext.RouteData);
}
public override void OnResultExecuted(ResultExecutedContext filterContext)
{
//base.OnResultExecuted(filterContext);
Message(filterContext.RouteData);
}
public override void OnResultExecuting(ResultExecutingContext filterContext)
{
// base.OnResultExecuting(filterContext);

Message(filterContext.RouteData);
}
public void Message(RouteData route)
{
var _controllerName = route.Values["controller"];
var _methodName = route.Values["action"];
var _returnMessage = String.Format("controller = {0},action {1}", _controllerName, _methodName);

Debug.WriteLine(_returnMessage);
}


}
}

{/codecitation}

4. Custom Action filter class contains one method called Message. This method is simply writing name of the controller and action on Debug output.
5. On Action of TestController apply this custom Action filter.

{codecitation class="brush: csharp; gutter: true;" width="650px"}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;
using System.Web.Mvc.Ajax;
using usingActionFilter;

namespace usingActionFilter.Controllers
{
public class TestController : Controller
{

[CustomActionFilter]
public string TestingActionFilter()
{
return "D";
}

}
}

{/codecitation}

6. See the output in Debug mode

Custom Action filter is writing name of the Controller and Action on Debug.

For Better understanding of, how custom Action filter is working, put breakpoint and run the application.

Conclusion

This article gave an introduction of Action Filter in ASP.Net MVC framework. This also explained how to create a custom Action filter.

Thank you

About the Author

Dhananjay Kumar Description :I done my engineering from Anand Engineering college Agra in 2007. I am MCTS WCF, MCTS MOSS Development, I am MCTS Web Development . I am native of Jamshedpur. Currently Please feel free to contact me regarding any clarification of my article at Dhananjay.25july@gmail.com Occupation : Software Engineer Company : UST Global. Location : India Follow me at twitter : http://twitter.com/dhananjay25