Binding of itemArray removes Links

GoJS
1

Cheers,

in my project I’m using a binding to the itemArray to create a bunch of ports for a node. The array is not directly linked, but computed by the converter function. However, triggering the binding removes all existing links to ports inside the items.

So it’s something like:

new go.Binding("itemArray","", function(v,n){
  arr = [];
  //now fill it
  return arr;
})

If I change it so it does not create a new array and the references stay the same, the connected links don’t vanish. However, the template for the ports is not updated as the references have not changed -.-

The ports created have the same id and stuff, so there is actually no reason for the links to disappear. I think that updating the template first removes everything and propagates that to the links before creating the new content.

Any thoughts on this?

Many Thanks,
Malte

2

That does seem wrong – we’ll investigate.

3

I made a workaround:

new go.Binding("itemArray","", function(v, n) {
  n.part.data["_tmp"] = n.part.data["_tmp"] || {}; // create temporary data on first touch
  data["_tmp"].arr = data["_tmp"].arr || []; // create temporary array on first touch
  var arr = data["_tmp"].arr;
  // loop over given array
  for (var i=0; i<GlobalArray.length; i++) {
    var port = GlobalArray[i];
    if (i >= arr.length) { // add new elements on first touch, this is the portId
      arr.push({id:("port"+i)})
    }
    arr[i].name = port.name; // change some values
  }
  return arr;
})

It seems it is important to keep the reference unchanged. Replacing
data["_tmp"].arr = data["_tmp"].arr || [];
with
data["_tmp"].arr = [];
so starting with a complete new array, results in the behavior explained above.

4

Changing the itemTemplate also removes all drawn links to the ports although the itemArray is unchanged.

The 2 templates I used for testing are identical, so I just switched to a copy of the original template.

5

Yes, that’s wrong. We’ll look into it as soon as we get a chance later this morning, although the eclipse will probably distract us for an hour in the afternoon.
https://eclipse2017.nasa.gov/

6

I believe this will be fixed for 1.7.20. Setting Panel.itemArray (either directly or via binding) will call Panel.rebuildItemElements, which should now preserve any connected Links. I hope we’ll release later this week.