Blade Rendering Lifecycle

Blade uses the Model-view-presenter pattern to make Sitecore renderings feel like MVC, give you the control of MVC, but still fit within the normal Sitecore layout engine paradigms.

Anatomy of a Rendering Request with Blade

1. The Sitecore layout engine processes the layout details and selects the renderings to use (.cs, .cshtml, or .ascx)
2. The rendering, or View in Blade terms, knows what kind of ViewModel object it expects to get (via inheriting a generic Blade view class). The ViewModel may be any .NET type.
3. The View contacts the current Presenter Factory and requests a Presenter that is capable of delivering the ViewModel type the View needs to render. Presenters, in ASP.NET MVC terms, can be thought of as a single-action controller class - however unlike MVC they only produce the model, as the view is in front of them in the lifecycle.
4. The Presenter Factory resolves a Presenter, or depending on the factory implementation may use a Default Presenter that is fallen back to if no explicit presenter exists (e.g. Synthesis.Blade uses a default presenter that implicitly binds the context item to Synthesis item types without needing an explicit presenter for each type).
5. The Presenter resolves the ViewModel using whatever logic it has defined within it. The Presenter is a user-defined class that derives from IPresenter (or more likely a class that derives from IPresenter, such as SitecorePresenter or SynthesisPresenter that include extra niceties).
6. The View is provided the ViewModel from the Presenter and uses the values within to render itself

Simple Example

This example uses the Synthesis Presenter from Synthesis.Blade in a WebControl rendering to display an item whose template is My Template.

public class MyView : WebControlView<IMyTemplateItem>
{
    public void RenderModel(HtmlTextWriter writer)
    {
        writer.Write(Model.Title.RenderedValue);
    }
}

More Complex Example

This example uses a custom ViewModel and Presenter class

public class CustomViewModel
{
    public TestProperty { get; set; }
}

// note: if using Synthesis.Blade, use SynthesisPresenter here instead to get passed a typed item instead of Item
public class CustomPresenter : SitecorePresenter<CustomViewModel>
{
    protected override CustomViewModel GetModel(Blade.IView view, Item entity)
    {
        var model = new CustomViewModel();
        model.TestProperty = entity.DisplayName;
        return model;
    }
}

public class MyView : WebControlView<CustomViewModel>
{
    public void RenderModel(HtmlTextWriter writer)
    {
        writer.Write(Model.TestProperty);
    }
}

List Presenters

List presenters are a special type of presenter that allow you to take advantage of the same support that a SitecorePresenter does, but for renderings that have multiple items possible as their data source, for example a Lucene query data source in Sitecore 7, or a Sitecore Query based data source like query:./Articles/*. These expose a similar interface to SitecorePresenter but instead of an Item you get an Item[] parameter.