Angular incremental json problem

GoJS
1

i m working on a diagram in angular i need incremental json the diagram is a tree model so there are no links but on running this

this.diagram.addModelChangedListener(
e=>{
if (e.isTransactionFinished) {
// this records each Transaction as a JSON-format string
this.showIncremental(this.diagram.model.toIncrementalJson(e));
}
})

i get error

incremental
incremental.png1382×698 49.9 KB

2

The error indicates that you are using a GraphLinksModel, not a TreeModel.

3

but i m using a tree model

4

here tree

5

there is no link data array in it

6

In your Changed listener, when e.isTransactionFinished, see whether this.diagram.model instanceof go.GraphLinksModel is true.