Question

I need to execute some custom code before IControllerFactory.GetControllerInstance() is called.

I have looked at using HtppApplication.BeginRequest event, but that would execute my code for every request made to the server (include requests for static resources) – not ideal.

Is there an extensibility point in MVC that I can use to achieve this?

Answer 1

I cannot think why you need to do this, however, I think the simplest would be to create your own IControllerFactory. In MVC3, there is also new interface IControllerActivator.

public interface IControllerActivator
{
    /// <summary>
    /// When implemented in a class, creates a controller.
    /// </summary>
    IController Create(RequestContext requestContext, Type controllerType);
}

Here is an example using Unity,

public class UnityControllerFactory : DefaultControllerFactory
{
    /// <summary>
    /// 
    /// </summary>
    private readonly IUnityContainer _container;

    /// <summary>
    /// Initializes a new instance of the <see cref="UnityControllerFactory"/> class.
    /// </summary>
    /// <param name="container">The container.</param>
    /// <param name="controllerActivator">The controller activator.</param>
    public UnityControllerFactory(IUnityContainer container, IControllerActivator controllerActivator)
        : base(controllerActivator)
    {
        ////Guard.ArgumentNotNull(container, "container");
        _container = new PerRequestUnityContainer(container);
    }

    /// <summary>
    /// Releases the specified controller.
    /// </summary>
    /// <param name="controller">The controller to release.</param>
    public override void ReleaseController(IController controller)
    {
        if (controller != null)
        {
            _container.Teardown(controller);
        }

        base.ReleaseController(controller);
    }
}

public class UnityControllerActivator : IControllerActivator
{
    private readonly IUnityContainer _container;

    public UnityControllerActivator(IUnityContainer container)
    {
        ////Guard.ArgumentNotNull(container, "container");
        _container = new PerRequestUnityContainer(container);
    }

    /// <summary>
    /// When implemented in a class, creates a controller.
    /// </summary>
    /// <returns>
    /// The created controller.
    /// </returns>
    /// <param name="requestContext">The request context.</param><param name="controllerType">The controller type.</param>
    public IController Create(RequestContext requestContext, Type controllerType)
    {
        ////Guard.ArgumentNotNull(requestContext, "requestContext");
        ////Guard.ArgumentNotNull(controllerType, "controllerType");

        // do what ever you need to before creating your controller

        IController controller = (IController)_container.Resolve(controllerType);
        return controller;
    }
}

and somewhere in your startup/boot strapping process,

IUnityContainer container = ...;

// resolve our factory (and any of it's dependencies)
IControllerFactory factory = container.Resolve<IControllerFactory>();
ControllerBuilder.Current.SetControllerFactory(factory);