[news.eclipse.modeling.gmf] Creation of connections programatically

[Javier <j.cardenete@xxxxxxxxxx>]

Hello guys,

in my application, I want upon creation of certain nodes automatically 
create a connection pointing from an existing node to the new one.
These new nodes are added in the Canvas, so in the XXXEditPart (the one 
for the canvas) I'm controlling the event of adding that node (in method 
handleNotificationEvent(Notification notification)).

I implemented a class extending DeferredCreateConnectionViewCommand. 
When a new node is added, I create an instance of that command and 
execute it: the result works fine and the connection is right there. But 
this way of creating the connection has some problems:

- When I click on Undo the creation of the new node, the connection is 
also gone. But when I click redo, I get two connections pointing to the 
node: the one that existed, and a new one because an event of the type 
ADD to the canvas has been triggered again, so it is creation a command 
too. I get as many connections as the times I click undo/redo.

- If a delete the node, and then I click on Undo, I run into the same 
problem.

I tried several ways to solve this:
1 - In my command, handling doUndo() / doRedo() methods, but they aren't 
being called.
2 - In handleNotificationEvent(), upon the ADD event of the new edge, 
check its target and see if an Edge is already existing: right there I 
can't delete this new edge.

As alternative, I tried to create the Edge in the ViewFactory of the node:

Edge edge = getViewService().createEdge(EBKElementTypes.Link_4001,
				node.getDiagram(), 
((IHintedType)EBKElementTypes.Link_4001).getSemanticHint(),
				-1, false, getPreferencesHint());
		edge.setVisible(false);
		View aux = (View)node.getDiagram().getChildren().get(0);
edge.setSource((View)node.getDiagram().getChildren().get(0));
		edge.setTarget((View)node); //new node
		edge.persist();
		edge.setVisible(true);

The connection is created but shows up on the upper-left corner: after 
saving, closing and reopening the diagram, then it is correctly placed.

Anyone could give me a hint for solving this, or another method for 
creating the connection and not having problems with undo/redo mechanism?

Thank you guys,

javier.