FIX: Ensure that ChangeTrackerOptions doesn't get overriden

[nedmas]

Use _super() to reference parent getter in LeftAndMain.EditForm.js to ensure that ChangeTrackerOptions is modified and not overriden.

See #118 for initial bug report.

[hafriedlander]

Hi. Sorry, I was going to have a look at this on the back of that issue @chillu raised but you beat me to it. There's a couple of edge cases that aren't obvious that come from ChangeTrackerOptions being an object, and might need an Entwine API extension to fix nicely.

Objects in entwine properties are a bit dangerous, because javascript always passes them by reference instead of cloning them. Entwine also doesn't clone them when using them as default values.

The result is that this patch will repeatedly add that selector to the result every time getChangeTrackerOptions is called, so it'll be there once the first time it's called, twice the second, etc.

The right fix at the moment would look like:

$('.cms-edit-form').entwine({
  getChangeTrackerOptions: function() {
    // Figure out if we're still returning the default value
    var isDefault = (this.entwineData('ChangeTrackerOptions') === undefined);
    // Get the current options
    var opts = this._super();

    if (isDefault) {
      // If it is the default then...
      // clone the object (so we don't modify the original),
      var opts = $.extend({}, opts);
      // modify it,
      opts.ignoreFieldSelector +=', input[name=IsSubsite]';
      // then set the clone as the value on this element 
      // (so next call to this method gets this same clone)
      this.setChangeTrackerOptions(opts);
    }

    return opts;
});

This is super ugly though, non-obvious, and could maybe be handled better in the entwine layer.

[nedmas]

Thanks @hafriedlander that's a really useful insight into the way entwine works. I hadn't even considered that the selector would be added every time. I understand that your fix wouldn't be the best long term solution but would it be ok to incorporate into this PR so we have a fix for the time being? @chillu what do you think?

[nedmas]

Ok so I've update the PR with the code from @hafriedlander any chance this can get merged in @chillu?

[nedmas]

I don't wish to be a pain, but it would be really nice to get this merged in or at least get an update as to why it's not been merged already. I understand if it's just a time thing, and like I said I don't wish to be a pain just thought I'd ask.

[mateusz]

Oh man this indeed is hacky :-)

I'm happy to merge this in, but could you put Hamishes dissertation into the commit message, plus a link to this PR discussion? Also maybe put a link to this discussion into the code itself - this is a temporary measure and would be great if we make it clear.

[mateusz]

Yeah, thanks that will do :-)