How to achieve a dynamic controller and action method in ASP.NET MVC?

Question

In Asp.net MVC the url structure goes like

http://example.com/{controller}/{action}/{id}

For each "controller", say http://example.com/blog, there is a BlogController.

But my {controller} portion of the url is not decided pre-hand, but it is dynamically determined at run time, how do I create a "dynamic controller" that maps anything to the same controller which then based on the value and determines what to do?

Same thing with {action}, if the {action} portion of my url is also dynamic, is there a way to program this scenario?

Ilmenite

Answer 1

Absolutely! You'll need to override the DefaultControllerFactory to find a custom controller if one doesn't exist. Then you'll need to write an IActionInvoker to handle dynamic action names.

Your controller factory will look something like:

public class DynamicControllerFactory : DefaultControllerFactory
{
    private readonly IServiceLocator _Locator;

    public DynamicControllerFactory(IServiceLocator locator)
    {
        _Locator = locator;
    }

    protected override Type GetControllerType(string controllerName)
    {
        var controllerType = base.GetControllerType(controllerName);
            // if a controller wasn't found with a matching name, return our dynamic controller
        return controllerType ?? typeof (DynamicController);
    }

    protected override IController GetControllerInstance(Type controllerType)
    {
        var controller = base.GetControllerInstance(controllerType) as Controller;

        var actionInvoker = _Locator.GetInstance<IActionInvoker>();
        if (actionInvoker != null)
        {
            controller.ActionInvoker = actionInvoker;
        }

        return controller;
    }
}

Then your action invoker would be like:

public class DynamicActionInvoker : ControllerActionInvoker
{
    private readonly IServiceLocator _Locator;

    public DynamicActionInvoker(IServiceLocator locator)
    {
        _Locator = locator;
    }

    protected override ActionDescriptor FindAction(ControllerContext controllerContext,
                                                   ControllerDescriptor controllerDescriptor, string actionName)
    {
            // try to match an existing action name first
        var action = base.FindAction(controllerContext, controllerDescriptor, actionName);
        if (action != null)
        {
            return action;
        }

// @ray247 The remainder of this you'd probably write on your own...
        var actionFinders = _Locator.GetAllInstances<IFindAction>();
        if (actionFinders == null)
        {
            return null;
        }

        return actionFinders
            .Select(f => f.FindAction(controllerContext, controllerDescriptor, actionName))
            .Where(d => d != null)
            .FirstOrDefault();
    }
}

You can see a lot more of this code here. It's an old first draft attempt by myself and a coworker at writing a fully dynamic MVC pipeline. You're free to use it as a reference and copy what you want.

Edit

I figured I should include some background about what that code does. We were trying to dynamically build the MVC layer around a domain model. So if your domain contained a Product class, you could navigate to products\alls to see a list of all products. If you wanted to add a product, you'd navigate to product\add. You could go to product\edit\1 to edit a product. We even tried things like allowing you to edit properties on an entity. So product\editprice\1?value=42 would set the price property of product #1 to 42. (My paths might be a little off, I can't recall the exact syntax anymore.) Hope this helps!

Arnst

Hello @Ryan. I have tried to implemented your DynamicControllerFactory and DynamicActionInvoker from github.com/ryanohs/DynamicServices .During runtime i was asked for default constructor of DynamicControllerFactory 1st. Then i added one with empty implementation. But the parameterize constructer is never invoked and the _locater value is never set. So during invoking GetControllerInstance actionInvoker is not set due to null _locator. where have i done wrong. Need i have to give default value for _locator, or it is set set during runtime from elsewhere – Inca

anyone can elaborate the scenario when dynamic controller and dynamic action invoker would be required ? – Curarize

@Curarize theres alot of valid reason. I'm using it for so I can write compact services from the startup. Dynamically add a method tona generic crud controller instead of having to code one each time – Less

Answer 2

After a little more reflection, there may be a bit simpler way for you to handle the dynamic action names than my other answer. You'll still need to override the default controller factory. I think you could define your route like:

routes.MapRoute("Dynamic", "{controller}/{command}/{id}", new { action = "ProcessCommand" });

Then on your default/dynamic controller you'd have

public ActionResult ProcessCommand(string command, int id)
{
   switch(command)
   {
      // whatever.
   }
}

Arnst

how about dynamic controller? – Chump

This is very limited, what if you need to take in additional arguments – Less

Answer 3

You need to write your own IControllerFactory (or perhaps derive from DefaultControllerFactory) and then register it with ControllerBuilder.

Elation

I'm not sur because in the CreateController method of IControllerFactory , the RequestContext parameter already contains the bad route data. – Ramonaramonda

Answer 4

Iam working with it in .Core but i'll share it's MVC version for all, after that i will share the core version

                case OwnerType.DynamicPage:
                    var dp = mediator.Handle(new Domain.DynamicPages.DynamicPageDtoQuery { ShopId = ShopId, SeoId = seoSearchDto.Id }.AsSingle());
                    if (dp != null)
                    {
                        return GetDynamicPage(dp.Id);
                    }
                    break;

// some codes

    private ActionResult GetDynamicPage(int id)
    {
        var routeObj = new
        {
            action = "Detail",
            controller = "DynamicPage",
            id = id
        };

        var bController = DependencyResolver.Current.GetService<DynamicPageController>();
        SetControllerContext(bController, routeObj);
        return bController.Detail(id);
    }

// and

private void SetControllerContext(ControllerBase controller, object routeObj)
{
    RouteValueDictionary routeValues = new RouteValueDictionary(routeObj);

    var vpd = RouteTable.Routes["Default"].GetVirtualPath(this.ControllerContext.RequestContext, routeValues);



    RouteData routeData = new RouteData();

    foreach (KeyValuePair<string, object> kvp in routeValues)
    {
        routeData.Values.Add(kvp.Key, kvp.Value);
    }

    foreach (KeyValuePair<string, object> kvp in vpd.DataTokens)
    {
        routeData.DataTokens.Add(kvp.Key, kvp.Value);
    }


    routeData.Route = vpd.Route;
    if (routeData.RouteHandler == null)
        routeData.RouteHandler = new MvcRouteHandler();


    controller.ControllerContext = new ControllerContext(this.ControllerContext.HttpContext, routeData, controller);
}

Marketing