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c#asp.netasp.net-mvcfilteraction-filter
Cristiano Coelho
Cristiano Coelho

Reputation: 1735

ASP MVC Filters, where implement interface or not?

Just wondering, googling around how to use filters in asp mvc 4. I have found some people defines them like this:

public class CustomFilter : ActionFilterAttribute

And some like this:

public class CustomFilter : ActionFilterAttribute, IActionFilter

ActionFilterAttribute already has all operations to override, why should i implement the interface as well?

Also for example in the next code, at the end the filter is called again, why is this?

public class 

CustomActionFilter : ActionFilterAttribute, IActionFilter
{
    void IActionFilter.OnActionExecuting(ActionExecutingContext filterContext)


    {
        // TODO: Add your acction filter's tasks here

        // Log Action Filter Call
        MusicStoreEntities storeDB = new MusicStoreEntities();

        ActionLog log = new ActionLog()
        {
            Controller = filterContext.ActionDescriptor.ControllerDescriptor.ControllerName,
            Action = filterContext.ActionDescriptor.ActionName + " (Logged By: Custom 

Action Filter)",
            IP = filterContext.HttpContext.Request.UserHostAddress,
            DateTime = filterContext.HttpContext.Timestamp
        };

        storeDB.ActionLogs.Add(log);
        storeDB.SaveChanges();

        this.OnActionExecuting(filterContext);
    }
}

Upvotes: 3

Views: 1376

Answers (1)

Dave Alperovich
Dave Alperovich

Reputation: 32490

If you check the MSDN definition of ActionFilterAttribute you will see that it is an abstract class that inherits interfaces IActionFilter AND IResultFilter.

In effect inheriting from ActionFilterAttribute, 

public class CustomFilter : ActionFilterAttribute

is equivalent to inheriting class FilterAttribute and interfaces IActionFilter and IResultFilter

public class CustomFilter : FilterAttribute, IActionFilter, IResultFilter

and is no different than

public class CustomFilter : ActionFilterAttribute, IActionFilter, IResultFilter

So inheriting from ActionFilterAttribute is no different than inheriting from ActionFilterAttribute and IActionFilter.

Upvotes: 2

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