ShowNavigationItemController Class

A WindowController descendant that contains the ShowNavigationItem Action.

Namespace: DevExpress.ExpressApp.SystemModule

Assembly: DevExpress.ExpressApp.v25.2.dll

NuGet Package: DevExpress.ExpressApp

Declaration

C#
VB.NET

public class ShowNavigationItemController :
    WindowController,
    IModelExtender,
    IShowViewParametersCustomizer

Public Class ShowNavigationItemController
    Inherits WindowController
    Implements IModelExtender,
               IShowViewParametersCustomizer

Remarks

The ShowNavigationItemController is a part of the Navigation System. This Controller displays the ShowNavigationItem Action.

ASP.NET Core Blazor
Windows Forms

For details on the ShowNavigationItem Action, refer to the following topic: ShowNavigationItemController.ShowNavigationItemAction.

To customize the default behavior of the ShowNavigationItem Action, you can inherit from this Controller or subscribe to its events. In addition, you can access the Action to modify its behavior.

If you need to inherit from the ShowNavigationItemController, the following protected virtual methods are available for overriding:

Method	When is it called?	Description
`HasRights`	Invoked as a result of calling the `InitializeItems` method when populating the Navigation‘s Items collection.	Determines whether the application’s Security System grants permission to read the object(s) of the passed item’s View. If a Views \| View node describing the item’s View cannot be found, this method returns `true`. The items for which this method returns `false`, are disabled by the ShowNavigationItemController.SynchronizeItemsWithSecurity method.
`InitializeItems`	Called after the ShowNavigationItemController is activated.	Raises the ShowNavigationItemController.CustomInitializeItems event. Creates ChoiceActionItem objects and initializes them using information from the Application Model‘s IModelRootNavigationItems node. Marks the ChoiceActionItem as a start-up item if the corresponding NavigationItem node is set for the NavigationItems node’s IModelRootNavigationItems.StartupNavigationItem property. Invokes the `OnItemsInitialized` method to raise the ShowNavigationItemController.ItemsInitialized event. Calls the ShowNavigationItemController.GetStartupNavigationItem method to mark one of the ShowNavigationItem Action’s items as a start-up item, if none of the items are marked as yet. Sets the ShowNavigationItem Action’s SingleChoiceAction.SelectedItem property to the item that is marked as a start-up item. This item will be selected when the navigation control is shown for the first time.
`OnItemsInitialized`	Called after the ShowNavigationItem Action’s Items collection is populated via the `InitializeItems` method.	Raises the ShowNavigationItemController.ItemsInitialized event.
`ShowNavigationItem`	Called by the ShowNavigationItem Action’s SingleChoiceAction.Execute event handler.	Raises the ShowNavigationItemController.CustomShowNavigationItem event. Creates a View using information of the passed Item’s ChoiceActionItem.Data property cast as ViewShortcut if the `Handled` parameter of the `CustomShowNavigationItem` event handler is not set to `false`.

Public members are described individually in the documentation.

To ascertain whether the Controller is active, use the Controller.Active property (see How to: Detect a Lookup List View in Code). If you need to know the reason for its deactivation or activation at runtime, use the DiagnosticInfo Action.

Information on the ShowNavigationItemController and its ShowNavigationItem Action is available in the Application Model‘s ActionDesign node. To access it, use the Model Editor.