Understanding Action Filters in ASP.NET MVC

Creating a Simple Action Filter Example in Asp.Net MVC project

Step 1: -Open visual studio and click on File ->New->Project menu option

A new Project Dialog open.

Step 2: -In the left pane, select templates ->visualC# ->Web

Step 3: -Then, select ASP.NET WEB Application (.NET Framework)

Step 4: - Enter project name ActionFilterDemo in the Name Field and click ok to continue and you will see the dialog.

Step 5: - Select MVC option and check the MVC checkbox then click Ok

Example of HandleError in Action Filters

HandleError: - Handles error raised when a controller action is executed. ASP .NET MVC has a HandleError Attribute (Action Filter), which provides one of the simplest ways to handle errors. The Attribute of HandleError has a couple of properties which are useful in handling an exception and help in modifying the default behavior of HandleError Attribute.

Step 1: - I have create anActionFilterDemo project. Then select a View in shared Folder ->Error.cshtml. Error.cshtml file Use in ActionFilterdemo project

Step 2: -To add controller,Right-click on the controller folder in the solution explorer and select ADD -> Controller

It will display the Add Scaffold dialog.

step 3: -Select the MVC 5 Controller -> Empty option and click on ADD button

The Add controller dialog will show

Step 4: - set the Name to UserController and click on add button

UserController.cs

In UserController.cs use handleError Class type

namespaceActionFilterDemo.Controllers
{
    [HandleError]
	publicclassUserController : Controller
    {

	publicActionResultIndex()
       {
			returnView();
       }
    }
}

Then CustomError mode Add in Web.config file
 

<system.web>
    <compilation debug="true" targetframework="4.6.1" />
    <httpruntime targetframework="4.6.1" />
    <customerrors mode="On" />
</system.web>

Now Run in ActionFilterDemo Project.It will be display output in HandlesError

Example of Outputcache in Action Filters

Outputcache:- Caches the output of a controller action for a specified amount of time.Thebest ways of improving the performance in ASP.NET MVC Application is by caching. With help of caching, we can reduce hosting and the database Server round trips. Apply the Outputcache Action Filter either on Action Method or on the controller. outputCache attribute has several properties like a CacheProfile, Duration, Location, VaryByParam, VaryByHeader, NoStore etc.

Step 1: -To add controller, Right-click on the controller folder in the solution explorer and select ADD -> Controller

It will display the Add Scaffold dialog.

step 2: - select the MVC 5 Controller -> Empty option and click on ADD button

Step 3: - set the Name to CacheController and click on add button

CacheController.cs

The CacheController specifies the return value in 10 seconds.
 

namespaceActionFilterDemo.Controllers
{
	publicclassCacheController : Controller
    {
		// GET: Cache
        [OutputCache(Duration =10)]
publicstringIndex()
        {
			returnDateTime.Now.ToString();
        }
    }
}

Now Run in ActionFilterDemoProject. It will be display output in Outputcache

Example of Authorize in Action Filters

Authorize: - Enables you to restrict access to a particular user or role. All the action methods are accessible to the both anonymous and authenticated users. But, the action methods to be available only for authenticated and authorized users, then you need to use the AuthorizationFilter in MVC.

Step 1: -To add controller, Right-click on the controller folder in the solution explorer and select ADD -> Controller. It will display the Add Scaffold dialog.

step 2: - select the MVC 5 Controller -> Empty option and click on ADD button

Step 3: - set the Name to AuthorizeController and click on add button

AuthorizeController.cs

The Authorized allows only authorized users to log in the application.
 

namespaceActionFilterDemo.Controllers
{
publicclassAuthorizeController : Controller
    {
// GET: Authorize
	publicActionResultIndex()
        {
			returnView();
        }
        [Authorize]
	publicActionResultSaved()
        {
			returnView();
        }
        [AllowAnonymous]
	publicActionResultNot_saved()
        {
			returnView();
        }
	publicActionResultLogin()
        {
			returnView();
        }

	}
}

Create a View

Right-click on the Method ?Add View.

We haveCreated a Saved, Not Save and Login Empty View in Authorize Folder.

Login.cshtml

In Views/Authorize/login.cshtml, replace the contents of the file with the following code to replace the text about ASP.NET and MVC with text about this application.

<system.web>
    <compilation debug="true" targetframework="4.6.1" />
    <httpruntime targetframework="4.6.1" />
    <customerrors mode="On" />
    <authentication mode="Forms">
      <forms loginurl="/Authorize/Login"></forms>
    </authentication>
  </system.web>

Now Run ActionFilterDemo Project. The Output of Login Page then write a Url in Authorize/Save. Redirect to save Method.It will be display output in Authorize.

Conclusion

This blog depicts about action filters which wraps the action method execution. It is an additional processing, such as providing extra data to the action method, inspecting the return value, or cancelling execution of the action method.