Create a Context Menu Using C#

Introduction

You can add a context menu to an IEntity in Studio Pro or to a IDocument, such as microflows and pages. These context menus will appear under a menu named after the extension that contains them (for example, MyExtension) and can modify the items they relate to. This is achieved by specifying the type when creating the extension.

You can download the example in this how-to in this GitHub repository.

Prerequisites

Before you start this how-to, it is recommended to Create a Menu Extension Using C# first.

Creating an Entity Context Menu Extension Class

1. Open the project you previously created by following Create a Menu Extension Using C#.

2. Add a new class to the project named MyEntityContextMenuExtension.cs.

3. Replace the code in the file with the following:

   namespace MyCompany.MyProject.MendixExtension;
   
   [method: ImportingConstructor]
   [Export(typeof(Mendix.StudioPro.ExtensionsAPI.UI.Menu_V2.ContextMenuExtension<>))]
   class MyEntityContextMenuExtension(IMessageBoxService messageBoxService) : Mendix.StudioPro.ExtensionsAPI.UI.Menu_V2.ContextMenuExtension<IEntity>
   {
       MenuViewModel? disabledMenu;
   
       public override IEnumerable<MenuViewModel> GetContextMenus(IEntity entity)
       {
           var nudgeDownLeft = new MenuViewModel("Left", () => NudgeIt(entity, right: false, down: true));
           var nudgeDownLeftRight = new MenuViewModel("Right", () => NudgeIt(entity, right: true, down: true) );
           var nudgeDown = new MenuViewModel("Down", [nudgeDownLeft, nudgeDownLeftRight]);
   
           var nudgeUpLeft = new MenuViewModel("Left", () => NudgeIt(entity, right: false, down: false));
           var nudgeUpRight = new MenuViewModel("Right", () => NudgeIt(entity, right: true, down: false));
           var nudgeUp = new MenuViewModel("Up", [nudgeUpLeft, nudgeUpRight])
           {
               Separator = MenuSeparator.Before
           };
   
           yield return new MenuViewModel("Nudge it!", [nudgeDown, nudgeUp]);
   
           // new group
           var randomRenameString = new MenuViewModel("Random string", () => RenameEntity(entity, number: false));
           var randomRenameNumber = new MenuViewModel("Random number", () => RenameEntity(entity, number: true));
   
           yield return new MenuViewModel("Randomly rename", [randomRenameString, randomRenameNumber]);
   
           // show location
           yield return new MenuViewModel("Show location", () => ShowLocation(entity, messageBoxService));
   
           var showName = new MenuViewModel("Show current name", () => messageBoxService.ShowInformation(entity.Name));
           // "Randomly rename" was added previously, thus it will trigger an exception when collected if uncommented
           //yield return new MenuViewModel("Randomly rename", [showName]);
   
           // Enabling a disabled menu
           disabledMenu ??= new MenuViewModel("Disabled menu", () =>
           {
               messageBoxService.ShowInformation("I'm enabled now. But not for long!");
               disabledMenu!.IsEnabled = false;
           }){ IsEnabled = false };
           var enablingMenu = new MenuViewModel("Enable disabled menu", () => disabledMenu.IsEnabled = true );
   
           yield return new MenuViewModel("Enabling menus", [disabledMenu, enablingMenu]);
   
       }
   
       void NudgeIt(IEntity entity, bool right, bool down)
       {
           var incrementRight = right ? 20 : -20;
           var incrementDown = down ? 20 : -20;
           using var transaction = CurrentApp!.StartTransaction("nudge with context menu");
           entity.Location = new Location(entity.Location.X + incrementRight, entity.Location.Y + incrementDown);
   
           transaction.Commit();
       }
   
       void RenameEntity(IEntity entity, bool number)
       {
           using var transaction = CurrentApp!.StartTransaction("rename with context menu");
   
           entity.Name = number ? $"E_{new Random().Next()}" : $"E_{Guid.NewGuid().ToString().Replace("-", "")}";
   
           transaction.Commit();
       }
       static void ShowLocation(IEntity entity, IMessageBoxService messageBoxService) => messageBoxService.ShowInformation($"X: {entity.Location.X}, Y: {entity.Location.Y}");
   }

The code above creates a series of context menu items for any entity. The menus allow you to:

• Rename the entity
• Change the entity's location on the canvas
• Display entity information in a message box
• Enable a previously disabled menu item

Adding a Context Menu to a Document

You can also add a context menu to a document. To do this, specify the type IDocument in your context menu extension.

namespace MyCompany.MyProject.MendixExtension;

[method: ImportingConstructor]
[Export(typeof(ContextMenuExtension<>))]
class MyDocumentContextMenuExtension(IMessageBoxService messageBoxService) : ContextMenuExtension<IDocument>
{
    public override IEnumerable<MenuViewModel> GetContextMenus(IDocument document)
    {
        if (document is IMicroflow microflow)
            yield return new MenuViewModel("This document is a  microflow", () => messageBoxService.ShowInformation(microflow.Name));

        else if (document is IPage page)
            yield return new MenuViewModel("This document is a  page", () => messageBoxService.ShowInformation(page.Name));
    }
}