Detecting duplicate nodes on an external drop

GoJS
1

Continuing the discussion from Highlight links between nodes:

2

How are you deciding whether a node was a duplicate or not?

Maybe something like:

    "ExternalObjectsDropped": function(e) {
        e.subject.each(function(node) {
            if (e.diagram.nodes.any(function(n) { return n.category === node.category && !n.isSelected; })) {
                 ...
            }
          });
    }

Or substitute category with whatever criteria that you are using.

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3

Great. This worked. But the dropped item does not get deleted. Its stays hooked up to the mouse pointer.

4

Sounds like there was an error in your “ExternalObjectsDropped” event handler.

5

There isn’t any error in the event handler. Subsequent code executes fine. Would you suggest to check anything else ?

6

Are you using the debug version of the GoJS library?

Without the “ExternalObjectsDropped” DiagramEvent handler, does a drop work normally?

What is it that you are trying to do if you detect a duplicate? If you are modifying the dropped node(s), you should be able to modify them right then/there. If you want to cancel the whole drop, call e.diagram.currentTool.doCancel().

7

hi walter, I am using the release version. Drop works normally with “ExternalObjectsDropped” DiagramEvent handler.
After adding the recent line of code(doCancel()), I am able to find duplicate but not able to cancel the drop. The item still drops to the canvas.

e.subject.each(function(node) {
            if (e.diagram.nodes.any(function (n) {
                return n.category === node.category && (n.category === 'Start' || n.category === 'End') && !n.isSelected;
              
            })) {
               e.diagram.currentTool.doCancel();
                ShowPopupMessage("error", "Cannot drop duplicate block.");
            }
        });
1 Like
8

The problem is resolved now. I used below 2 lines to fix.

e.diagram.commandHandler.deleteSelection();
                e.diagram.currentTool.doCancel();

Thank you for all the assistance. :smile:

1 Like