addModelChangedListener is working but data not storing into database

GoJS
22

I told you not to assign the node keys manually, but you still are. If you really want to do that you need to do it in both models.

I deleted your “ExternalObjectsDropped” DiagramEvent listener and added this initialization in load:
myDiagram.model.makeUniqueKeyFunction = function(model, obj) {
return getguid();
};
myTreeView.model.makeUniqueKeyFunction = function(model, obj) {
return getguid();
};