There are two ways to add/move/delete model elements:

  • Use com.nomagic.magicdraw.openapi.uml.ModelElementsManager
  • Call direct functions on Elements

The ModelElementsManager is the singleton utility class which checks com.nomagic.uml2.ext.magicdraw.classes.mdkernel.Element editing permissions and the session existence before executing the function. Also, it performs a check, if an element can be added to a parent. If the ModelElementsManager is not used, a programmer must perform these checks in the code explicitly.

Adding and moving functions are similar with mostly one - move functions does more checking such as checking for a name conflict if com.nomagic.uml2.ext.magicdraw.classes.mdkernel.NamedElement is moved. The general rule would be to use an adding function for newly created Element(s) and use a moving function for already existing elements in the model.
More advanced model refactoring functions are described in the Refactoring model elements page.

Adding element to owner with ModelElementsManager

For adding a new model Element into a model, use the addElement(Element, Element) method provided by the ModelElementsManager. 

    Project project = ...;
    Class classA = ...;
    Package package = ...;
    // create a new session
    SessionManager.getInstance().createSession(project, "Add class into package");
    try
    {
        // add a class into a package
        ModelElementsManager.getInstance().addElement(classA, package);
    }
    catch (ReadOnlyElementException e)
    {
    }
    // apply changes and add a command into the command history. 
    SessionManager.getInstance().closeSession(project);
If a given model element cannot be added into a given parent, java.lang.IllegalArgumentException is thrown. For example, an com.nomagic.uml2.ext.magicdraw.classes.mdkernel.Operation cannot be added into a com.nomagic.uml2.ext.magicdraw.classes.mdkernel.Package or an Operation cannot be added into a not locked for editing com.nomagic.uml2.ext.magicdraw.classes.mdkernel.Class (in the server project). If an element or parent is null, java.lang.IllegalArgumentException also is thrown. If a given element is not editable (read-only), com.nomagic.magicdraw.openapi.uml.ReadOnlyElementException is thrown.

Adding element to owner using a direct function

    Element parent = ...;
    Class classA = ...;
    Project project = ...;
    // create a new session 
    SessionManager.getInstance().createSession(project, "Add class into parent"); 
    if (parent.canAdd(classA))
    {
        classA.setOwner(parent);
    }
    // apply changes and add a command into the command history. 
    SessionManager.getInstance().closeSession(project);


Moving element with ModelElementsManager

For moving an existing model Element, use the moveElement(Element, Element) method provided by the ModelElementsManager. 

    Project project = ...;
    Class classA = ...;
    Package package = ...;
    // create a new session
    SessionManager.getInstance().createSession(project, "Add class into package");
    try
    {
        // add a class into a package
        ModelElementsManager.getInstance().moveElement(classA, package);
    }
    catch (ReadOnlyElementException e)
    {
    }
    // apply changes and add a command into the command history. 
    SessionManager.getInstance().closeSession(project);

If a given model element cannot be moved into a given parent, java.lang.IllegalArgumentExceptionis thrown. For example, an Operation cannot be moved into a Package or an Operation cannot be moved into a not locked for editing Class (in the server project). If an element or parent is null, java.lang.IllegalArgumentException also is thrown. If a given element is not editable (read-only), com.nomagic.magicdraw.openapi.uml.ReadOnlyElementException is thrown.

Moving element using a direct function

    Element parent = ...;
    Class classA = ...;
    Project project = ...;
    // create a new session 
    SessionManager.getInstance().createSession(project, "Add class into parent"); 
    if (com.nomagic.uml2.ext.jmi.helpers.ModelHelper.canMoveChildInto(parent, classA))
    {
        classA.setOwner(parent);
    } 
    // apply changes and add a command into the command history. 
    SessionManager.getInstance().closeSession(project);

Removing element with ModelElementsManager

    Class classA = ...;
    Project project = ...;
    // create a new session 
    SessionManager.getInstance().createSession(project, "Remove class"); 
    try
    {
         // remove a class
        ModelElementsManager.getInstance().removeElement(classA);
    }
    catch (ReadOnlyElementException e)
    {
    }
    // apply changes and add a command into the command history. 
    SessionManager.getInstance().closeSession(project);


Removing element using direct call

    Class classA = ...;
    Project project = ...;
    // create a new session 
    SessionManager.getInstance().createSession(project, "Remove class"); 
    if (classA.isEditable()))
    {
         classA.dispose();
    }
    // apply changes and add a command into the command history. 
    SessionManager.getInstance().closeSession(project);

 You can find the code examples in <modeling tool installation directory>\openapi\examples\hierarchyremover

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