Controller.Active Property

Provides access to a collection of reason/value pairs used to activate or deactivate a Controller, or determine its active state.

Namespace: DevExpress.ExpressApp

Assembly: DevExpress.ExpressApp.v24.1.dll

NuGet Package: DevExpress.ExpressApp

Declaration

C#

[Browsable(false)]
public BoolList Active { get; }

VB.NET

<Browsable(False)>
Public ReadOnly Property Active As BoolList

Property Value

Type	Description
BoolList	A BoolList object that represents a collection of key/value elements.

Remarks

A Controller’s active state may depend on many factors such as the current view or user permissions. Any individual factor can prevent activation.

The Active property stores the collection of factors that affect the active state. Each element of this collection contains a string value (factor description) and the corresponding Boolean value that permits or prohibits activation. If all collection elements are true, the Controller is active.

The following methods allow you to determine whether a Controller is currently active:

• Use the Active property value in a conditional expression.
• Read the Active property value. Use the return object’s BoolList.ResultValue property.

C#

MyViewController myController;
//...
BoolList activeList = myController.Active;
if (activeList) {
    //...
}

To deactivate a Controller, use the following members of the BoolList object (Active property value):

• Call the BoolList.SetItemValue method. Pass the reason for deactivation as the first parameter. Set the second parameter to a Boolean expression or simply to false.
• Use the [_key_] operator to get or set the specified key’s value.

C#

MyViewController myController;
//...
BoolList activeList = myController.Active;
activeList["myKey"] = false;

The following members can activate an inactive Controller:

• Call the BoolList.RemoveItem method. Pass the key (factor description). If the collection no longer contains any false values, the Controller becomes active.
• Call the BoolList.SetItemValue method. Pass a factor description and ‘true’ as the corresponding value.

C#

MyViewController myController;
//...
BoolList activeList = myController.Active;
activeList["disablingKey"] = true;

To activate or deactivate an Action instead of the entire Controller, use the Action’s ActionBase.Active property.

Deactivate a Built-In Controller

You may want to disable a built-in controller. Do this to disable features that you do not wish to use or if the controller’s logic conflicts with your business logic. You can choose one of the following techniques to achieve this.

• Create a new Controller

  In the new controller’s overridden OnFrameAssigned method, find the controller that you want to disable and use its Active property to deactivate the controller:

  using DevExpress.ExpressApp;
  using DevExpress.ExpressApp.SystemModule;
  
  public class DisableRecordsNavigationController : ViewController {
      protected override void OnFrameAssigned() {
          base.OnFrameAssigned();
          var recordsNavigationController = Frame.GetController<RecordsNavigationController>();
          if (recordsNavigationController != null) {
              recordsNavigationController.Active["Explicitly disabled"] = false;
          }
      }
  }
  

  When you deactivate a controller this way, you can target the controller’s base type even if it has platform-specific descendants (RecordsNavigationController has an ASP.NET Core Blazor-specific BlazorRecordsNavigationController descendant). However, this method is not suitable if the controller has some undesirable logic in its own OnFrameAssigned override. In that case, use the following method.

• Inherit from the built-in Controller

  Create a descendant of the built-in controller and deactivate it in the OnFrameAssigned method:

  using DevExpress.ExpressApp.Blazor.SystemModule;
  
  public class CustomRecordsNavigationController : BlazorRecordsNavigationController {
      protected override void OnFrameAssigned() {
          // keep the line below commented out to disable the base controller's OnFrameAssigned logic
          //base.OnFrameAssigned();
          Active["Explicitly disabled"] = false;
      }
  }
  

  In this case, you need to specify the platform-specific descendant of the controller you want to deactivate as your custom controller’s base class. This technique gives you more control over specifying when the controller should be active.

Note

If you deactivate a controller in the OnFrameAssigned method, it disables the controller entirely. If you want to deactivate this controller in specific views, refer to the following topic: Define the Scope of Controllers and Actions - Activate or Deactivate a Controller.

Related GitHub Examples

The following code snippet (auto-collected from DevExpress Examples) contains a reference to the Active property.

Note

The algorithm used to collect these code examples remains a work in progress. Accordingly, the links and snippets below may produce inaccurate results. If you encounter an issue with code examples below, please use the feedback form on this page to report the issue.

C#

XAF_Non-Persistent-Objects-Edit-Linked-Persistent-Objects-Demo/CS/NonPersistentObjectsDemo.Module/Controllers/ProductViewNestedCollectionController.cs#L20

if(linkUnlinkController != null) {
    linkUnlinkController.Active["NotInProductView"] = !(pcs != null && (pcs.MasterObject is ProductView));
}

VB.NET

XAF_Non-Persistent-Objects-Edit-Linked-Persistent-Objects-Demo/VB/NonPersistentObjectsDemo.Module/Controllers/ProductViewNestedCollectionController.vb#L22

If linkUnlinkController IsNot Nothing Then
    linkUnlinkController.Active("NotInProductView") = Not (pcs IsNot Nothing AndAlso (TypeOf pcs.MasterObject Is ProductView))
End If