Create a Custom Filter in ASP.NET MVC

Create a Custom Filter in ASP.NET MVC

• In ASP.NET MVC, custom filters are handled by a base class named as ActionFilterAttribute.
• This ActionFilterAttribute class implements both IActionFilter & IResultFilter.
• Although ASP.NET MVC has numerous built-in filters but in many cases, there comes a need for custom rules or handles.

• In such cases, we need to design our custom Filters using ActionFilterAttribute.
• In your Solution Explorer, right click on the Main project and click on Add and then click on New Folder.

• It will create a New Folder in your project, rename it to ActionFilter.
• Now, right click on this ActionFilter folder and click Add and then Class, as we want to add new class in it, as shown in below figure:

• It will open up a new pop up window, where you need to select class and then give it a name.
• I have given a name TEPCustomActionFilter.cs to my Filter class file, as shown in below figure:

• Now click the Add Button and a new class will be added in your ActionFilter folder and will also open up in your workspace.
• It will have some default code in it, as shown in below figure:

• Let's add some code in our newly created filter class, as shown in below figure:

• We need to derive this class from ActionFilterAttribute that why I have extended the class name.
• We need to include System.Web.Mvc in order to use ActionFilterAttribute.
• In the class, I have created a simple function in which I am displaying a text on the output debug pane, after the execution of my project.
• So, we have created our custom filter, now it's time to add it in our StudentController which we have created in Tut # 6: Create a new Controller in ASP.NET MVC.
• Open your StudentController.cs file and place this filter in it, as shown in below figure:

• First of all, we need to add our package TEPwebApp.ActionFilter, ActionFilter is the name of our folder we created for our custom filter.
• Now before the StudentController class, place the code for our newly created custom Filter [TEPCustomActionFilter].
• Now run your project and after website opened in the browser, stop your project and check your Output Pane.
• You will find the text, as shown in below figure:

• I have highlighted our Text in the above figure.
• So, our filter has executed after the StudentController class and it has displayed the info.
• Such Filters are used for listening purposes, we can listen different types of data through them.
• Have a look at this video to get better understanding of How to Create Custom Filter in ASP.NET MVC: