How to create a custom filter in ASP.NET MVC?
In this article, We are going to discuss how to create and use a Custom Filter in ASP.NET MVC Application.
Implement an appropriate filter interface for which you want to create a custom filter and derive the FilterAttribute class to utilize that class as an attribute to generate custom filter attributes.
As the example, Create a custom exception filter by implementing IExceptionFilter and the FilterAttribute class. Create a custom authorization filter by implementing an IAuthorizatinFilter interface and a FilterAttribute class.
class MyErrorHandler : FilterAttribute, IExceptionFilter
{
public override void IExceptionFilter.OnException(ExceptionContext filterContext)
{
Log(filterContext.Exception);
base.OnException(filterContext);
}
private void Log(Exception exception)
{
//log exception here..
}
}
To enhance the functionality of built-in filters, you can derive a built-in filter class and override an appropriate method.
By deriving the built-in HandleErrorAttribute class and overriding the OnException method, we can create a custom exception filter that logs every unhandled exception, as seen below.
class MyErrorHandler : HandleErrorAttribute
{
public override void OnException(ExceptionContext filterContext)
{
Log(filterContext.Exception);
base.OnException(filterContext);
}
private void Log(Exception exception)
{
//log exception here..
}
}
The MyErrorHandler attribute can now be applied at the global, controller, or action method level, just as the HandleError attribute.
[MyErrorHandler]
public class HomeController : Controller
{
public ActionResult Index()
{
return View();
}
}
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