MVC and pipelines

Current version: 9.0

This topic describes the pipelines and the processors Sitecore MVC uses.

MVC-specific processors

Some standard Sitecore pipelines have processors that are specifically used for Sitecore MVC. This table shows what they are:

Pipeline	Processors
Initialize	`InitializeGlobalFilters` – this processor sets up the following hooks in the MVC global filters: `ActionExecuting` `ActionExecuted` `ResultExecuting` `ResultExecuted` `Exception` `InitializeControllerFactory` – this processor installs a custom controller factory (`IControllerFactory`) into the MVC runtime to facilitate greater control over MVC request handling and controller creation. `InitializeRoutes` – sets up the default Sitecore route handler (fall-through: `{*pathInfo}`) and decorates existing routes with Sitecore-specific route keys.
HttpBeginRequest	`TransferRoutedRequest`: This processor is placed before the `LayoutResolver` processor. If the request matches a route in the MVC route table, the pipeline stops executing and makes the MVC request handler take over. Only custom routes are considered. The Sitecore fall-through route (`{*pathInfo}`) is ignored by the processor (otherwise all requests would match and be processed by MVC). `TransferMvcLayout`: This processor is placed after the `LayoutResolver` processor. If the resolved layout file name has an extension matching one of the extensions specified in the `MvcSettings.ViewExtensions` setting, the pipeline stops executing and makes the MVC request handler take over. `TransferControllerRequest`: This processor is placed after the `TransferMvcLayout` processor. If no layout has been resolved, the `Controller` field of the current item is inspected. If it contains a value, the pipeline stops executing and makes the MVC request handler take over. The specified controller is then responsible for rendering the item.

Pipeline

Processors

Initialize

InitializeGlobalFilters – this processor sets up the following hooks in the MVC global filters:
- ActionExecuting
- ActionExecuted
- ResultExecuting
- ResultExecuted
- Exception
InitializeControllerFactory – this processor installs a custom controller factory (IControllerFactory) into the MVC runtime to facilitate greater control over MVC request handling and controller creation.
InitializeRoutes – sets up the default Sitecore route handler (fall-through: {*pathInfo}) and decorates existing routes with Sitecore-specific route keys.

HttpBeginRequest

TransferRoutedRequest: This processor is placed before the LayoutResolver processor. If the request matches a route in the MVC route table, the pipeline stops executing and makes the MVC request handler take over. Only custom routes are considered. The Sitecore fall-through route ({*pathInfo}) is ignored by the processor (otherwise all requests would match and be processed by MVC).
TransferMvcLayout: This processor is placed after the LayoutResolver processor. If the resolved layout file name has an extension matching one of the extensions specified in the MvcSettings.ViewExtensions setting, the pipeline stops executing and makes the MVC request handler take over.
TransferControllerRequest: This processor is placed after the TransferMvcLayout processor. If no layout has been resolved, the Controller field of the current item is inspected. If it contains a value, the pipeline stops executing and makes the MVC request handler take over. The specified controller is then responsible for rendering the item.

MVC-specific pipelines

The following table lists all of the Sitecore pipelines that are only used by MVC:

Pipeline	Description
RequestBegin	This is the first action of an MVC request after the request has been passed down from the main `HttpRequest` pipeline. A PageContext is created and assigned to the current thread. If the request is a form post, the associated form handler (if any) is executed.
RequestEnd	This is the last action of an MVC request. This pipeline is not currently used.
CreateController	This pipeline is called by the `SitecoreControllerFactory` to create a controller for the current route selected by the MVC request handler. If the requested item (`PageContext.Item`) specifies a controller (in the `__Controller Name` field), this controller is instantiated and returned. Otherwise, an instance of the default `SitecoreController` is returned.
ActionExecuting	This pipeline executes before an MVC controller action is executed. This pipeline is not currently used.
ActionExecuted	This pipeline executes after an MVC controller action is executed. This pipeline is not currently used.
ResultExecuting	This pipeline executes before an MVC result is executed. This pipeline is not currently used.
ResultExecuted	This pipeline executes after an MVC result is executed. This pipeline is not currently used.
Exception	This pipeline executes after the MVC runtime catches an unhandled exception. This pipeline is not currently used. If you attach a custom processor to this pipeline, this processor should set the `ExceptionContext.ExceptionHandled` property on the `ExceptionArgs` object that is handed to the processor. Otherwise, Sitecore will do standard error handling.
GetPageItem	This pipeline resolves the item that was requested using route information. If the item cannot be resolved from the route, `Context.Item` is used.
BuildPageDefinition	This pipeline builds the initial `PageDefinition` by using the XML-based layout definition of the `Renderings` field on the page item.
GetPageRendering	This pipeline selects the rendering to use as the root rendering of the page for creating the output of the current request. Currently, the root rendering is selected based solely on the current device (`PageContext.Device`).
GetRenderer	This pipeline transforms an abstract rendering definition (rendering) into an object that can render output back to the client (renderer).
GetModel	This pipeline creates the model object to use when rendering an MVC view. This is typically a ASP.NET MVC 3 Razor view. If the pipeline returns no model, the view receives an instance of `EmptyModel`. This triggers a meaningful error message if the .cshtml file contains the `@model` directive and therefore expects a model.
RenderPlaceholder	This pipeline is called as part of the `Html.Sitecore().Placeholder` extension method. It handles nested placeholders, when applicable. By default, the pipeline finds all renderings matching the specified placeholder name in the current `PageDefinition` and renders them. It only renders child renderings if the rendering explicitly renders them, typically by calling `Html.Sitecore().Inner()`.
RenderRendering	The pipeline renders the specified rendering. This pipeline handles caching and sets up the `IRenderingContext` for accessing source items of the renderings. This supports nested renderings.

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