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A DD4T.net Implementation - AJAX Component Controller

Most commonly, a Component Presentation is rendered within the context of a Page. This implies the Component Presentation is present on the Tridion page in the Tridion Content Manager backend. DD4T publishes the Page and generates its model, and at the same time, it generates the model for all Component Presentations on the Page.

These embedded Component Presentations cannot be displayed on their own outside the context of the Page that surrounds them. However, in practice we have sometimes the requirement to display a Dynamic Component Presentation (DCP) on its own – independent of the Page it appears on. This requires, as the name already implies, that the Component Presentation is published as Dynamic Component Presentation, with a Dynamic CT that specifies content will be “Published as a Dynamic Component”.

When published, DD4T will generate the model for such Component on its own and the Component model will be available in the Content Delivery database, ready to be retrieved independently. For example, as the result of dynamic query for content.

This post presents a way of displaying such DCPs using the DD4T MVC framework. These DCPs can be used in AJAX context to either provide the Component model to the calling Javascript client, or return actual rendered HTML directly.

I chose to expose the Component controller URL as an endpoint of my web-application. The corresponding MVC .net route, from RouteConfig.cs, is the following:

    routes.MapRoute(
        name: "DCP",
        url: "{controller}/{action}/{publication}/{component}/{view}",
        constraints: new
        {
            controller = @"\w{1,50}",
            action = @"\w{1,50}",
            publication = @"\d{1,3}",
            component = @"\d{1,6}",
            view = @"\w{1,50}"
        }
    );

The concept is relatively simple: the endpoint URL contains all input parameters I need to render the DCP:
  • controller and action for MVC .net to know which class/method instantiate and call;
  • publication and component ids to know which DCP to load;
  • view name to know which view to dispatch to;

The constraints section is there to enforce already at the .net MVC routing level some regular expressions for accepted parameters. As such, the publication and component ids must be integers, the other parameters are strings, each of an enforced minimum/maximum length.

The beauty of this model is that I can reuse the Component controllers between the cases when the CP is embedded on the Page as well as when it is published as DCP. The following example Component controller shows just that:

    public class DeviceController : MyControllerBase
    {
        public ActionResult Index(int? publication, int? component, string view)
        {
            Device device;
            string viewName;
            ResolveModelAndView<Device>(publication, component, view, out device, out viewName);

            // More processing...

            return View(viewName, device);
        }
    }

Notice the nullable int types in the method signature. This is a must in order for the method to fire and be called when the Component Presentation is embedded on the Page. DD4T calls this method with all parameters null, since at that moment, the IComponentPresentation object is already available in RouteData (but more about that in a future post). The RouteConfig.cs must thus also contain a route mapping for a simple standard controller, action call:

    routes.MapRoute(
        name: "Default",
        url: "{controller}/{action}/{id}",
        defaults: new { action = "Index", id = UrlParameter.Optional }
    );

The above endpoint can be called from any HTTP client using a URL similar to:

    http://my.server.com/Device/Index/123/456/FullDetail

In the current form, the response will be the actual HTML rendered by the FullDetail view. With minimal modification, the URL could also return the actual XML/JSON model of the underlying Component.



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