Support optgroups in select list

What kind of support you are expecting? Does Entity reference field use any hierarchy?

It isn't possible because this module is called Taxonomy container. Let's move it to Entity reference issue queue.

Optgroups are still not supported... Is there any way I can do this?

I'm also looking for a way to get optgroups in an entity reference select field. Anyone stumble across a method of achieving this?

Here's a patch that adds optgroups to the views selection handler. To use, group an entityreference view by desired field, then use that view on the reference field.

I have not tested this thoroughly, and I suppose it could be coded more elegantly.

the patch

Sorting does not seem to work correctly.

Nope, turns out my view was configured badly.

$rows = array_combine(array_keys($result), $this->view->result);

In some cases this line behaves wrongly. $result is sorted differently than $this->view->result if you use any post-query result altering modules like:
- views PHP (filtering / sorting / grouping)
- computed field (filtering / sorting / grouping)
etc.

Closed #2277193: Options from views and grouping field and #2758537: Views Select List Grouping as duplicates.

$rows = array_combine(array_keys($result), $this->view->result);

In some cases this line behaves wrongly. $result is sorted differently than $this->view->result if you use any post-query result altering modules like:
- views PHP (filtering / sorting / grouping)
- computed field (filtering / sorting / grouping)
etc.