Model data should not have any references to a Diagram or any part of a diagram

GoJS
#1

I am currently writing some unittest via using gojs models.

I have following code in typescript.

let model = new go.GraphLinksModel();
let node = new go.Node();
let nodeData = model.copyNodeData(node); // warning here

model.startTransaction(“Add node”);
model.addNodeData(nodeData);
model.commitTransaction(“Add node”);

There is no problem if I get the model from a real diagram by using the way any sample provided. However, I get following log warning now.

LOG: ‘Warning: found GraphObject or Diagram reference when copying model data on property “port” of data object: Node#1114
Model data should not have any references to a Diagram or any part of a diagram, such as: Node#1114’
LOG: ‘Warning: found GraphObject or Diagram reference when copying model data on property “bc” of data object: Node#1114
Model data should not have any references to a Diagram or any part of a diagram, such as: Node#1114’
LOG: ‘Warning: found GraphObject or Diagram reference when copying model data on property “locationObject” of data object: Node#1114
Model data should not have any references to a Diagram or any part of a diagram, such as: Node#1114’
LOG: ‘Warning: found GraphObject or Diagram reference when copying model data on property “self” of data object: Node#1114
Model data should not have any references to a Diagram or any part of a diagram, such as: Node#1114’

Any idea? This won’t break the test but just a little bit annoying.

Thanks,
Chuan

#2

No, that warning is important for you to recognize that something is very wrong.

In this case it should be clear that you are trying to add a Node to the model, rather than some node data, a JavaScript Object.

Each Node should belong to a Diagram.

Each Node.data object should belong to a Model. (Actually it will be in its Model.nodeDataArray.)

The whole point of models is that in a model-view architecture there should be no references to a view within the model. There are many advantages of maintaining such a separation, including the ability to easily serialize the model.

#3

Thanks for quick reply, Walter.

I am still a little bit confused.

The parameter of copyNodeData is required to be a Node. The output is the copied data with it and will be add to model later. So are you saying that I cannot create a node by using node constructor but must bind a node to a diagram?

Can you help me modify the usage of my code? I don’t want to create a view since I only want to test the model part. How should I do the correct thing in order to add a nodedata correctly to a model without any view/diagram?

-Chuan

#4

No, the documentation at http://gojs.net/latest/api/symbols/Model.html#copyNodeData is clearly talking about data, not about Nodes. That’s why “Data” is part of the method name. Also see http://gojs.net/latest/release/go.d.ts:

copyNodeData(nodedata: Object): Object;

Yes, you can do a lot of stuff with Models without creating any Diagrams. But maybe less than you’d like.

#5

Wait, am I misunderstanding this? Seems true.

Parameters:
{Object} nodedata
a JavaScript object represented by a node, group, or non-link.

-Chuan

#6

I change my code to following now. But get different error now. I am using Karma + PhantomJS + Jasmine for my test.

TypeError: Attempted to assign to readonly property.

let model = new go.GraphLinksModel();
let node = new go.Node();
let nodeData = model.copyNodeData(node.data); // no warning now
nodeData[“test”] = “something”; // error here

model.startTransaction(“Add node”);
model.addNodeData(nodeData);
model.commitTransaction(“Add node”);

#7

Yes, and what’s the value of nodeData?

That’s because node.data is null.

The word “represent” derives from the word “present”. If “X is represented by Y”, then Y presents a symbol or rendering of X. In GoJS (or any model-view system) X is some piece of data or computer-memory and Y is what you see on screen or paper.
Ceci n’est pas une pipe

#8

You are right, my nodeData is not defined. Actually I don’t need to create a dummy node at all. Can just model.copyNodeData({})