protected Command getCreateCommand(CreateElementRequest req) {
     if (XXXElementTypes.B_2001 == req.getElementType()) {
          EObject root = req.getContainer();
	  if (root instanceof View) {
	       root = ((View) root).getElement();
          }
		
	  A_Node a = XXXFactory.eINSTANCE.createA_Node();
			
	  CreateElementRequest r = new CreateElementRequest(req.getEditingDomain(), a, XXXElementTypes.A_1001);
	  return getGEFWrapper(new A_NodeAndB_NodeCreateCommand(r, this.getHost(), root));
     }
     
     if (XXXElementTypes.A_1001 == req.getElementType()) {
          return getGEFWrapper(new A_NodeCreateCommand(req));
     }
     
     return super.getCreateCommand(req);
}

protected CommandResult doExecuteWithResult(IProgressMonitor monitor, IAdaptable info) throws ExecutionException {
		A_Node a = (A_Node) getElementToEdit();
		B_Node b = XXXFactory.eINSTANCE.createB_Node();

		rootEObj.getNodes().add(a);
		doConfigureA(a, monitor, info);
	
		setElementToEdit(a);	
		
		CreateViewRequest.ViewDescriptor viewDescriptor = new CreateViewRequest.ViewDescriptor(
                           new EObjectAdapter(a), Node.class, null, XXXEditorPlugin.DIAGRAM_PREFERENCES_HINT); 
		CreateViewRequest viewRequest = new CreateViewRequest((viewDescriptor));
		Command cmd = rootEditPart.getCommand(viewRequest);
		cmd.execute();
		
		a.setAction(b);
		((CreateElementRequest) getRequest()).setContainer(a);
		doConfigure(b, monitor, info);

		((CreateElementRequest) getRequest()).setNewElement(b);
		return CommandResult.newOKCommandResult(b);
}

protected CommandResult doExecuteWithResult(IProgressMonitor monitor, IAdaptable info) throws ExecutionException {
	A_Node a = (A_Node) getElementToEdit();
	B_Node b = XXXFactory.eINSTANCE.createB_Node();

	rootEObj.getNodes().add(a);
	doConfigureA(a, monitor, info);
	
	setElementToEdit(a);	
		
	CreateViewRequest.ViewDescriptor viewDescriptor = new CreateViewRequest.ViewDescriptor(
                          new EObjectAdapter(a), Node.class, null, XXXEditorPlugin.DIAGRAM_PREFERENCES_HINT); 
	CreateViewRequest viewRequest = new CreateViewRequest((viewDescriptor));
	Command cmd = rootEditPart.getCommand(viewRequest);
	cmd.execute();

	// At this point an EditPart should be created corresponding to your semantic object 'a'.
	// 1. Locate this newly created edit part.
	// 2. Create a new CreateViewRequest just like before but this time we're creating a view for 'b'.
	// 3. Invoke newlyCreatedEditPart.getCommand(createViewRequestForB)
	// 4. Execute this command.
}

CreateViewRequest.ViewDescriptor viewDescriptor = new CreateViewRequest.ViewDescriptor(
                           new EObjectAdapter(a), Node.class, ((IHintedType)CreationElementTypes.A_1001).getSemanticHint(), CreationDiagramEditorPlugin.DIAGRAM_PREFERENCES_HINT); 

/**
 * @generated NOT
 */
protected void createDefaultEditPolicies() {
	super.createDefaultEditPolicies();
	installEditPolicy(EditPolicyRoles.SEMANTIC_ROLE, new FarmItemSemanticEditPolicy());
	installEditPolicy(EditPolicyRoles.CANONICAL_ROLE, new FarmCanonicalEditPolicy());
	installEditPolicy(EditPolicyRoles.CREATION_ROLE, new CustomCreationEditPolicy());
	// removeEditPolicy(org.eclipse.gmf.runtime.diagram.ui.editpolicies.EditPolicyRoles.POPUPBAR_ROLE);
}

package org.rmap.eclipse.gmf.bongo.diagram.edit.policies;

import org.eclipse.emf.ecore.EObject;
import org.eclipse.gef.commands.Command;
import org.eclipse.gef.commands.CompoundCommand;
import org.eclipse.gmf.runtime.diagram.core.edithelpers.CreateElementRequestAdapter;
import org.eclipse.gmf.runtime.diagram.ui.commands.ICommandProxy;
import org.eclipse.gmf.runtime.diagram.ui.editparts.IGraphicalEditPart;
import org.eclipse.gmf.runtime.diagram.ui.editpolicies.CreationEditPolicy;
import org.eclipse.gmf.runtime.diagram.ui.requests.CreateViewAndElementRequest;
import org.eclipse.gmf.runtime.diagram.ui.requests.CreateViewAndElementRequest.ViewAndElementDescriptor;
import org.eclipse.gmf.runtime.emf.type.core.IHintedType;
import org.eclipse.gmf.runtime.emf.type.core.requests.CreateElementRequest;
import org.eclipse.gmf.runtime.notation.Node;
import org.eclipse.gmf.runtime.notation.View;
import org.rmap.eclipse.gmf.bongo.diagram.edit.commands.CreateEggAfterChickenCommand;
import org.rmap.eclipse.gmf.bongo.diagram.providers.BongoElementTypes;

public class CustomCreationEditPolicy extends CreationEditPolicy {
	/**
	 * {@inheritDoc}
	 */
	protected Command getCreateElementAndViewCommand(CreateViewAndElementRequest request) {
		ViewAndElementDescriptor descriptor = request.getViewAndElementDescriptor();
		IHintedType eggHintedType = (IHintedType) BongoElementTypes.Egg_3001;
		IHintedType chickenHintedType = (IHintedType) BongoElementTypes.Chicken_2001;
		if (descriptor.getSemanticHint() == eggHintedType.getSemanticHint()) {
			IGraphicalEditPart farmEP = (IGraphicalEditPart) getHost();
			EObject farmSemanticObject = ((View) farmEP.getModel()).getElement();
			
			// First we need to create a chicken.
			CreateElementRequest chickenSemanticRequest = new CreateElementRequest(farmEP
					.getEditingDomain(), farmSemanticObject, chickenHintedType);
			CreateElementRequestAdapter chickenSemanticRequestAdapter = new CreateElementRequestAdapter(chickenSemanticRequest);
			ViewAndElementDescriptor chickenViewAndSemanticDescriptor = new ViewAndElementDescriptor(
					chickenSemanticRequestAdapter, Node.class, chickenHintedType.getSemanticHint(), farmEP
							.getDiagramPreferencesHint());
			CreateViewAndElementRequest createChickenViewAndSemanticRequest = new CreateViewAndElementRequest(chickenViewAndSemanticDescriptor);
			
			// Grab the location & size from the original request.
			createChickenViewAndSemanticRequest.setLocation(request.getLocation());
			createChickenViewAndSemanticRequest.setSize(request.getSize());
			
			Command createChickenViewAndSemanticCommand = farmEP.getCommand(createChickenViewAndSemanticRequest);
			
			// Create an egg afterwards.
			if (createChickenViewAndSemanticCommand.canExecute()) {
				CompoundCommand cc = new CompoundCommand();
				cc.add(createChickenViewAndSemanticCommand);
				cc.add(new ICommandProxy(new CreateEggAfterChickenCommand(farmEP)));				
				return cc;
			}
		} 
		return super.getCreateElementAndViewCommand(request);	
	}	
}

package org.rmap.eclipse.gmf.bongo.diagram.edit.commands;

import org.eclipse.core.commands.ExecutionException;
import org.eclipse.core.runtime.IAdaptable;
import org.eclipse.core.runtime.IProgressMonitor;
import org.eclipse.emf.ecore.EObject;
import org.eclipse.gef.commands.Command;
import org.eclipse.gmf.runtime.common.core.command.CommandResult;
import org.eclipse.gmf.runtime.diagram.core.edithelpers.CreateElementRequestAdapter;
import org.eclipse.gmf.runtime.diagram.ui.editparts.IGraphicalEditPart;
import org.eclipse.gmf.runtime.diagram.ui.requests.CreateViewAndElementRequest;
import org.eclipse.gmf.runtime.diagram.ui.requests.CreateViewAndElementRequest.ViewAndElementDescriptor;
import org.eclipse.gmf.runtime.emf.commands.core.command.AbstractTransactionalCommand;
import org.eclipse.gmf.runtime.emf.type.core.IHintedType;
import org.eclipse.gmf.runtime.emf.type.core.requests.CreateElementRequest;
import org.eclipse.gmf.runtime.notation.Node;
import org.eclipse.gmf.runtime.notation.View;
import org.rmap.eclipse.gmf.bongo.diagram.providers.BongoElementTypes;

public class CreateEggAfterChickenCommand extends AbstractTransactionalCommand {
	
	private IGraphicalEditPart farmEP;
	
	public CreateEggAfterChickenCommand(IGraphicalEditPart farmEP) {
		super(farmEP.getEditingDomain(), "creates-an-egg-after-a-chicken", null);
		this.farmEP = farmEP;		
	}

	/**
	 * {@inheritDoc}
	 */
	protected CommandResult doExecuteWithResult(IProgressMonitor monitor, IAdaptable info) throws ExecutionException {
		// In my case a farm can only contain chickens, so I select the last
		// edit part added to the farm which should correspond to the chicken
		// created from the previous command.
		if (!farmEP.getChildren().isEmpty()) {
			Object lastAddedEP = farmEP.getChildren().get(farmEP.getChildren().size() - 1);
			IGraphicalEditPart chickenEP = (IGraphicalEditPart) lastAddedEP;
			
			// Create a new egg!
			IHintedType eggHintedType = (IHintedType) BongoElementTypes.Egg_3001;
			EObject chickenSemanticObject = ((View) chickenEP.getModel()).getElement();
			CreateElementRequest eggSemanticRequest = new CreateElementRequest(chickenEP
					.getEditingDomain(), chickenSemanticObject, eggHintedType);
			CreateElementRequestAdapter eggSemanticRequestAdapter = new CreateElementRequestAdapter(eggSemanticRequest);
			ViewAndElementDescriptor eggViewAndSemanticDescriptor = new ViewAndElementDescriptor(
					eggSemanticRequestAdapter, Node.class, eggHintedType.getSemanticHint(), chickenEP
							.getDiagramPreferencesHint());
			CreateViewAndElementRequest createEggViewAndSemanticRequest = new CreateViewAndElementRequest(eggViewAndSemanticDescriptor);			
			Command createEggViewAndSemanticCommand = chickenEP.getCommand(createEggViewAndSemanticRequest);
			if (createEggViewAndSemanticCommand.canExecute()) {
				createEggViewAndSemanticCommand.execute();
				return CommandResult.newOKCommandResult();
			}
		}
		
		return CommandResult.newErrorCommandResult("Could not create egg after the chicken.");
	}		
}