How to: Define a Menu Command on a Modeling Diagram

In Visual Studio Ultimate, you can define additional menu items that appear when the user right-clicks a UML diagram. You can control whether the menu command appears and is enabled when the user right-clicks any element on the diagram, and you can write code that runs when the user selects the menu item. You can package these extensions into a Visual Studio Integration Extension (VSIX) and distribute it to other Visual Studio Ultimate users.


Defining the menu command

To create a menu command for a UML designer, you must create a class that defines the behavior of the command, and embed the class in a Visual Studio Integration Extension (VSIX). The VSIX acts as a container that can install the command. There are two alternative methods of defining a menu command:

  • Create a menu command in its own VSIX using a project template. This is the quicker method. Use it if you do not want to combine your menu commands with other types of extension such as validation extensions, custom toolbox items, or gesture handlers.

  • Create separate menu command and VSIX projects. Use this method if you want to combine several types of extension into the same VSIX. For example, if your menu command expects the model to observe specific constraints, you could embed it into the same VSIX as a validation method.

To create a menu command in its own VSIX

  1. In the New Project dialog box, under Modeling Projects, select Command Extension.

  2. Open the .cs file in the new project and modify the CommandExtension class to implement your command.

    For more information, see Implementing the Menu Command.

  3. You can add additional commands to this project by defining new classes.

  4. Test the menu command by pressing F5. For more information, see Executing the Menu Command.

  5. Install the menu command on another computer by copying the file bin\*\*.vsix that is built by your project. For more information, see Installing the Menu Command.

To create a separate menu command in a class library (DLL) project

  1. Create a Class Library project, either in a new Visual Studio solution, or in an existing solution.

    1. On the File menu, point to New and then click Project.

    2. Under Installed Templates, click Visual C# or Visual Basic. In the middle column, click Class Library.

    3. Set Solution to indicate whether you want to create a new solution or to add a component to a VSIX solution that you have already opened.

    4. Set the project Name and Location and click OK.

  2. Add the following references to your project.


    What this allows you to do


    Define components by using Managed Extensibility Framework (MEF).


    Read and change properties of model elements.


    Create model elements, modify shapes on diagrams.


    Define model event handlers.

    Encapsulate series of changes to your model. For more information, see How to: Link Model Updates using Transactions.


    (not always required)

    Access additional diagram elements for gesture handlers.


    Required only for commands on layer diagrams. For more information, see Creating Extensions for Layer Diagrams.

    Define commands on a Layer diagram.

  3. Add a class file to the project and set its content to the following code.


    Change the namespace, class name, and the value returned by Text to your preference.

    If you define multiple commands, they appear on the menu in alphabetical order of the class names.

    using System.ComponentModel.Composition;   
    using System.Linq;
    using Microsoft.VisualStudio.ArchitectureTools.Extensibility.Presentation;
    using Microsoft.VisualStudio.ArchitectureTools.Extensibility.Uml;
    using Microsoft.VisualStudio.Modeling.ExtensionEnablement;
    using Microsoft.VisualStudio.Uml.AuxiliaryConstructs;
    using Microsoft.VisualStudio.Uml.Classes; 
        // ADD other UML namespaces if required
    namespace UMLmenu1 // CHANGE
      // DELETE any of these attributes if the command
      // should not appear in some types of diagram.
      // [LayerDesignerExtension] // if you have installed Feature Pack 1
      // All menu commands must export ICommandExtension:
      [Export (typeof(ICommandExtension))]
      // CHANGE class name – determines order on menu.
      public class Menu1 : ICommandExtension
        public IDiagramContext DiagramContext { get; set; }
        public void QueryStatus(IMenuCommand command)
        { // Set command.Visible or command.Enabled to false
          // to disable the menu command.
          command.Visible = command.Enabled = true;
        public string Text
          get { return "MENU COMMAND LABEL"; }
        public void Execute(IMenuCommand command)
          // A selection of starting points:
          IDiagram diagram = this.DiagramContext.CurrentDiagram;
          foreach (IShape<IElement> shape in diagram.GetSelectedShapes<IElement>())
          { IElement element = shape.Element; }
          IModelStore modelStore = diagram.ModelStore;
          IModel model = modelStore.Root;
          foreach (IElement element in modelStore.AllInstances<IClass>()) 
          { }

    For more information about what to put in the methods, see Implementing the Menu Command.

You must add your menu command to a VSIX project, which acts as a container for installing the command. If you want, you can include other components in the same VSIX.

To add a separate menu command to a VSIX project

  1. You do not need this procedure if you have created the menu command with its own VSIX.

  2. Create a VSIX project, unless your solution already has one.

    1. In Solution Explorer, right-click the solution, point to Add, and then click New Project.

    2. Under Installed Templates, expand Visual C# or Visual Basic, then click Extensibility. In the middle column, click VSIX Project.

  3. Set the VSIX project as the startup project of the solution.

    In Solution Explorer, right-click the VSIX project and then click Set as StartUp project.

  4. In source.extension.vsixmanifest, under Content, add the class library project as a MEF Component.

    1. Open source.extension.vsixmanifest

    2. Click Add Content.

    3. At Select a content type, select MEF Component.

    4. At Select a source, click Project and select the name of your class library project.

  5. Click Select Editions and select the Visual Studio editions you want your extension to run on.

  6. Set the name and descriptive fields of the VSIX. Save the file.

Implementing the Menu Command

The menu command class implements the required methods for ICommandExtension.

string Text { get; }

Return the label of your menu item.

void QueryStatus(IMenuCommand command);

Called when the user right-clicks in the diagram.

This method should not change the model.

Use DiagramContext.CurrentDiagram.SelectedShapes to determine whether you want the command to appear and be enabled.


  • command.Visible to true if the command must appear in the menu when the user right-clicks in the diagram

  • command.Enabled to true if the user can click the command in the menu

  • command.Text to set the menu label dynamically

void Execute (IMenuCommand command);

Called when the user clicks your menu item, if it is visible and enabled.


Accessing the Model in Code

Including the following declaration in your menu command class:

[Import] public IDiagramContext DiagramContext { get; set; }


The declaration of IDiagramContext allows you to write code in your methods that accesses the diagram, current selection, and model:

IDiagram diagram = this.DiagramContext.CurrentDiagram;
foreach (IShape<IElement> shape in diagram.GetSelectedShapes<IElement>())
{ IElement element = shape.Element; ... }
IModelStore modelStore = diagram.ModelStore;
IModel model = modelStore.Root;
foreach (IElement element in modelStore.AllInstances<IUseCase>()) {...}

The elements of the UML model are all available through the API. From the current selection or from the root of the model, you can access all the other elements. For more information, see How to: Navigate the UML Model and Programming with the UML API.

If you are dealing with a sequence diagram, see also How to: Edit Sequence Diagrams by Using the UML API.

The API also allows you to change the properties of elements, delete elements and relationships, and create new elements and relationships.

By default, each change that you make in your Execute method will be performed in a separate transaction. The user will be able to undo each change separately. If you want to group the changes into a single transaction, use a ILinkedUndoTransaction as described in How to: Link Model Updates using Transactions.

Use the UI Thread for Updates

In some cases it can be useful to make updates to the model from a background thread. For example, if your command loads data from a slow resource, you can perform the loading in a brackground thread so that the user can see the changes while they are in progress, and cancel the operation if it is necessary.

However, you should be aware that the model store is not thread safe. You should always use the user interface (UI) thread to make updates, and if it is possible, prevent the user from making edits while the background operation is in progress. For an example, see How to: Update a UML Model from a Background Thread.

Executing the Menu Command

For test purposes, execute your command in debug mode.

To test the menu command

  1. Press F5, or on the Debug menu, click Start Debugging.

    An experimental instance of Visual Studio starts.

    Troubleshooting: If a new Visual Studio does not start:

    • If you have more than one project, make sure that the VSIX project is set as the Startup project of the solution.

    • In Solution Explorer, right-click the startup or only project, and then click Properties. In the project properties editor, click the Debug tab. Make sure that the string in the Start external program field is the full pathname of Visual Studio, typically:

      C:\Program Files\Microsoft Visual Studio 10.0\Common7\IDE\devenv.exe

  2. In the experimental Visual Studio, open or create a modeling project, and open or create a modeling diagram. Use a diagram that belongs to one of the types that are listed in the attributes of your menu command class.

  3. Right-click anywhere on the diagram. Your command should appear in the menu.

    Troubleshooting: If the command does not appear on the menu, make sure that:

    • The menu command project is listed as a MEF component in the Content list in source.extensions.manifest in the VSIX project.

    • The parameters of the Import and Export attributes are valid.

    • The QueryStatus method is not setting the command.Enabled or Visible fields to false.

    • The type of model diagram that you are using (UML class, sequence, and so on) is listed as one of the menu command class attributes [ClassDesignerExtension], [SequenceDesignerExtension] and so on.

Installing and uninstalling an extension

You can install a Visual Studio extension both on your own computer and on other computers.

To install an extension

  1. In your computer, find the .vsix file that was built by your VSIX project.

    1. In Solution Explorer, right-click the VSIX project, and then click Open Folder in Windows Explorer.

    2. Locate the file bin\*\YourProject.vsix

  2. Copy the .vsix file to the target computer on which you want to install the extension. This can be your own computer or another one.

    The target computer must have one of the editions of Visual Studio that you specified in source.extension.vsixmanifest.

  3. On the target computer, double-click the .vsix file.

    Visual Studio Extension Installer opens and installs the extension.

  4. Start or restart Visual Studio.

To uninstall an extension

  1. On the Tools menu, click Extension Manager.

  2. Expand Installed Extensions.

  3. Select the extension, and then click Uninstall.

Rarely, a faulty extension fails to load and creates a report in the error window, but does not appear in Extension Manager. In that case, you can remove the extension by deleting the file from:



The following example shows the code for a menu command that will interchange the names of two elements on a class diagram. This code must be built in a Visual Studio Extension project and installed as described in the previous sections.

using System.Collections.Generic; // for IEnumerable
using System.ComponentModel.Composition;
  // for [Import], [Export]
using System.Linq; // for IEnumerable extensions
using Microsoft.VisualStudio.ArchitectureTools.Extensibility.Presentation;
  // for IDiagramContext
using Microsoft.VisualStudio.ArchitectureTools.Extensibility.Uml;
  // for designer extension attributes
using Microsoft.VisualStudio.Modeling.Diagrams;
  // for ShapeElement
using Microsoft.VisualStudio.Modeling.ExtensionEnablement;
  // for IGestureExtension, ICommandExtension, ILinkedUndoContext
using Microsoft.VisualStudio.Uml.Classes;
  // for class diagrams, packages

/// <summary>
/// Extension to swap names of classes in a class diagram.
/// </summary>
namespace SwapClassNames
  // Declare the class as an MEF component:
  // Add more ExportMetadata attributes to make
  // the command appear on diagrams of other types.
  public class NameSwapper : ICommandExtension
  // MEF required interfaces:
  public IDiagramContext Context { get; set; }
  public ILinkedUndoContext LinkedUndoContext { get; set; }

  /// <summary>
  /// Swap the names of the currently selected elements.
  /// </summary>
  /// <param name="command"></param>
  public void Execute(IMenuCommand command)
    // Get selected shapes that are IClassifiers -
    // IClasses, IInterfaces, IEnumerators.
    var selectedShapes = Context.CurrentDiagram
    if (selectedShapes.Count() < 2) return;

    // Get model elements displayed by shapes.
    IClassifier firstElement = selectedShapes.First().Element;
    IClassifier lastElement = selectedShapes.Last().Element;

    // Do the swap in a transaction so that user
    // cannot undo one change without the other.
    using (ILinkedUndoTransaction transaction =
    LinkedUndoContext.BeginTransaction("Swap names"))
    string firstName = firstElement.Name;
    firstElement.Name = lastElement.Name;
    lastElement.Name = firstName;

  /// <summary>
  /// Called by Visual Studio to determine whether
  /// menu item should be visible and enabled.
  /// </summary>
  public void QueryStatus(IMenuCommand command)
    int selectedClassifiers = Context.CurrentDiagram
    command.Visible = selectedClassifiers > 0;
    command.Enabled = selectedClassifiers == 2;

  /// <summary>
  /// Name of the menu command.
  /// </summary>
  public string Text
    get { return "Swap Names"; }


See Also


How to: Define and Install a Modeling Extension

Extending UML Models and Diagrams

How to: Define a Drop and Double-Click Handler on a Modeling Diagram

How to: Define a Custom Modeling Toolbox Item

How to: Define Validation Constraints for UML Models

How to: Edit Sequence Diagrams by Using the UML API

Programming with the UML API

Other Resources

Sample: Command to Align Shapes on a UML Diagram