Dojo 1.4.2 Tree Grid "expando click" event? persist state?

Question

Question:

Given a DOJO TreeGrid, how can I capture the event when a user clicks the expando ("+") button to expand a row, and store the specific row number or associated item's identifier? I'd like to do this for the express purpose of completely deleting the TreeGrid from the DOM, rebuilding it, and restoring it's state once rebuilt (i.e. programmatically expanding the rows that the user has previously expanded).

Background:

So I've got a custom DOJO TreeGrid, hooked up to a custom QueryReadStore, in my app. It was constructed using the following tutorial:

http://www.ibm.com/developerworks/web/library/wa-dojotreegrid/index.html?ca=drs-

Pretty interesting tutorial, but it might be irrelevant to my question because it doesn't really squash any functionality, it only seems to augment it.

Anyway, googling around for a moment, I found a nice function in the DOJO forums that I can use to programmatically expand a row, given the specific row index. Works perfectly.

The problem is that I haven't been able to find a good way to capture the expando click event, and relate it to a specific "parent item row" index in the grid.

Details aside, I'd like to get the row index of every row that the user has expanded, into an array (and delete the index of a row that the user collapses, obviously), so I can destroy this TreeGrid, and faithfully rebuild it, with the user's selections expanded properly.

I'm not really a novice to DOJO, but I'm certainly no expert by any means. I've done a fair bit of googling, and FireBugging, and haven't really been able to find anything that I can use to do this.

Suggestions? Anybody done something similar before? Stupid question with obvious answer that I've missed? I'm totally misguided and am going about it all wrong? Thanks everybody!

Answer 1

Something similar to this would probably work, this is how the dijit.Tree implementation wouldve looked;

var expandedNodes = {}
dijit.tree._onExpandoClick = function (args /* object wrap for args.node */) {
   var treeNode = args.node,
       path = treeNode.getTreePath(),
       id = treeNode.getIdentity();

   expandedNodes[id] = path;

}

I am not 100% sure im being strictly correct but for the TreeGrid you will have to look through code of dojox/grid/_TreeView.js (link). The _setOpen would be an entrypoint from which you can 'hook' the onclick action. from there, find the expandoCell.openStates hash, this is a true/false variable set, indexed by itemId. This hash is most likely what you need as your state