How to: Create Elements and Relationships

Article
02/04/2013

In the program code for an extension to Visual Studio Ultimate, you can create and delete elements and relationships.

Create a Model Element

Namespace Imports

You must include the following using statements.

The creation methods are defined as extension methods in this namespace:

using Microsoft.VisualStudio.ArchitectureTools.Extensibility.Uml;

Obtain the owner of the element you want to create

A model forms a single tree, so that every item has one owner, except for the model root. The model root is of type IModel, which is a type of IPackage.

If you are creating an element that will be displayed in a particular diagram, for example, the user's current diagram, you should usually create it in the package that is linked to that diagram. For example:

IPackage linkedPackage = Context.CurrentDiagram.Element as IPackage;

This table summarizes the ownership of common model elements:

Element to be Created	Owner
IActor, IUseCase, IComponent, IClass, IInterface, IEnumeration IActivity, IInteraction	IPackage, IModel
IAttribute, IOperation	IClass, IInterface
IPart, IPort	IComponent
IAction, IObjectNode	IActivity
ILifeline, IMessage, ICombinedFragment	IInteraction

Invoke the Create method on the owner

The method name is of the form: CreateOwnedType(). For example:

IUseCase usecase1 = linkedPackage.CreateUseCase();

Some types have more complex creation methods, particularly in Sequence Diagrams. See How to: Edit Sequence Diagrams by Using the UML API.

For some types of element, you can change the owner of an element during its lifetime, using SetOwner(newOwner).

Set the name and other properties

usecase1.Name = "user logs in";

Example

 using Microsoft.VisualStudio.Uml.Classes;
 using Microsoft.VisualStudio.Uml.Extensions;
 ...
  void InstantiateObserverPattern (IPackage package, string namePrefix)
  {    IInterface observer = package.CreateInterface();
       observer.Name = namePrefix + "Observer";
       IOperation operation = observer.CreateOperation();
       operation.Name = "Update";
       IClass subject = package.CreateClass();
       subject.Name = namePrefix + "Subject"; ...

Create an Association

To create an association

Obtain the owner of the association, which is usually the package or model containing the source end of the relationship.
Invoke the required Create method on the owner.

Set the relationship's properties such as its name.

For example:

IAssociation association = subject.Package.CreateAssociation(subject, observer);
association .Name = "Observes";

Set the properties of each end of the relationship. There are always two MemberEnds. For example:

association .MemberEnds[0].Name = "subject";   // role name
association .MemberEnds[1].Name = "observers"; // role name
association .MemberEnds[1].SetBounds("0..*");         
            // multiplicity defaults to "1"
association.MemberEnds[0].Aggregation = AggregationKind.Composite;

Create a Generalization

IGeneralization generalization = 
  subclass.CreateGeneralization(superClass);

Delete an Element, Relationship, or Generalization from the Model

anElement.Delete();

When you delete an element from a model:

Every relationship that links to it is also deleted.
Every shape that represented it on a diagram is also deleted.