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How to correctly delete Part [message #1802900]

Mon, 18 February 2019 17:41

João Pedro

Messages: 52
Registered: December 2014

Member

I'm iterating over a list of models and want to delete the corresponding ModelPart in some special cases.

2 questions about this:
1-How can I access the ModelPart within the Model? When I have the Part I can call part.getContent() to get the Model. Is there any similar method for getting the part from the model?

2-I found a way of getting the corresponding part by iterating over the Parent (root) part, which is a workaround in my opinion. However, even with the correct ModelPart I can't properly delete it. What am I doing wrong?

IRootPart<? extends Node> root = host.getRoot();
DeletionPolicy delPolicy = root.getAdapter(DeletionPolicy.class); 
init(delPolicy); //I'm inside a handler
						            
for (IVisualPart<? extends Node> a : new ArrayList<>(parent.getChildrenUnmodifiable())) {
			if (a instanceof ModelPart) {
											
				delPolicy.delete((IContentPart<? extends Node>) a);

			}
}

commit(delPolicy);

[Updated on: Mon, 18 February 2019 18:53]

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Re: How to correctly delete Part [message #1802907 is a reply to message #1802900]

Mon, 18 February 2019 19:15

Matthias Wienand

Messages: 230
Registered: March 2015

Senior Member

Hi Joao,

1) Each Viewer maintains a contentToPartMap where you can query the part that controls certain content.

2) Deletion logic depends on whether your ModelPart is parented at the root part or at another part:

https://github.com/eclipse/gef/blob/171559044bb8dcb7f88fd427f852efd39787978c/org.eclipse.gef.mvc.fx/src/org/eclipse/gef/mvc/fx/policies/DeletionPolicy.java#L134

		if (contentPartToDelete.getParent() instanceof IRootPart) {
			// remove content from viewer contents
			ChangeContentsOperation changeContentsOperation = new ChangeContentsOperation(
					viewer);
			List<Object> newContents = new ArrayList<>(viewer.getContents());
			newContents.remove(contentPartToDelete.getContent());
			changeContentsOperation.setNewContents(newContents);
			getRemoveContentChildrenOperation().add(changeContentsOperation);
		} else {
			// remove from content parent
			ContentPolicy parentContentPolicy = contentPartToDelete.getParent()
					.getAdapter(ContentPolicy.class);
			if (parentContentPolicy != null) {
				parentContentPolicy.init();
				parentContentPolicy
						.removeContentChild(contentPartToDelete.getContent());
				ITransactionalOperation removeFromParentOperation = parentContentPolicy
						.commit();
				if (removeFromParentOperation != null
						&& !removeFromParentOperation.isNoOp()) {
					getRemoveContentChildrenOperation()
							.add(removeFromParentOperation);
				}
			}
		}

If it is parented at the root part, then a ChangeContentsOperation should be created.

Otherwise, the parent part needs to have ContentPolicy bound as an adapter, and it needs to implement doRemoveContentChild() in order to collaborate with DeletionPolicy.

Any way, you should be able to find out what is going wrong by debugging DeletionPolicy.

Best of luck,
Matthias

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Re: How to correctly delete Part [message #1802941 is a reply to message #1802907]

Tue, 19 February 2019 11:18

João Pedro

Messages: 52
Registered: December 2014

Member

Thanks for the answer Matthias!

Where exactly is that contentToPartMap function? I can't see any reference to it.

Regarding point 2, managed to solve it with your advice! Thanks ;)

[Updated on: Tue, 19 February 2019 17:30]

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Re: How to correctly delete Part [message #1802963 is a reply to message #1802941]

Tue, 19 February 2019 18:09

João Pedro

Messages: 52
Registered: December 2014

Member

Regarding point 1, for future reference I could do it like this:

Map<Object, IContentPart<? extends Node>> content = getHost().getViewer().getContentPartMap();
						            
	 ModelPart modelPart = (ModelPart) content.get(model);

Thank you very much Matthias!

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