How to use dependency injection with an attribute?

Question

In an MVC project I\'m creating I have the following RequirePermissionAttribute that gets put on any action that needs specific permissions (it\'s been simplifi

Answer 1

I originally thought this was not possible, but I stand corrected. Here's an example with Ninject:

http://codeclimber.net.nz/archive/2009/02/10/how-to-use-ninject-to-inject-dependencies-into-asp.net-mvc.aspx

Update 2016-10-13

This is a pretty old question by now, and frameworks have changed quite a bit. Ninject now allows you to add bindings to specific filters based on the presence of specific attributes, with code like this:

// LogFilter is applied to controllers that have the LogAttribute
this.BindFilter(FilterScope.Controller, 0)
     .WhenControllerHas()
     .WithConstructorArgument("logLevel", Level.Info);
 
// LogFilter is applied to actions that have the LogAttribute
this.BindFilter(FilterScope.Action, 0)
     .WhenActionHas()
     .WithConstructorArgument("logLevel", Level.Info);
 
// LogFilter is applied to all actions of the HomeController
this.BindFilter(FilterScope.Action, 0)
     .WhenControllerTypeIs()
     .WithConstructorArgument("logLevel", Level.Info);
 
// LogFilter is applied to all Index actions
this.BindFilter(FilterScope.Action, 0)
     .When((controllerContext,  actionDescriptor) =>
                actionDescriptor.ActionName == "Index")
     .WithConstructorArgument("logLevel", Level.Info);

This is in keeping with the principle, argued by Mark Seeman and by the author of Simple Injector, which is that you should keep the logic of your action filter separate from the custom attribute class.

MVC 5 and 6 also make it far easier to inject values into attributes than it used to be. Still, separating your action filter from your attribute is really the best approach to take.