@Enola-guy thanks for your custom widget! I don't think we can merge this into the main library, though, until we have a JSON Schema-compliant approach (and in JSON Schema, enum must be an array, not a dict). Can you think of a JSON-schema-compliant way of using optgroups? For example, this might involve customizing the optgroups in uiSchema using something like this:

{
    "ui:groups": [
         { "title": "Theropods", "items": ["Tyrannosaurus", "Velociraptor"] },
         ...
     ]
}

This is just an idea -- let me know if you have any other thoughts / ways of doing this.

Thanks for the hint, I'm gonna try this, unfortunately it's not going to be DRY, but that's something. Will update the code today.

Hey late update, thank you so much it worked ui:groups did the work ! @epicfaace

Would you be interested in contributing your widget to this library as a PR?

I would be very interested ! I just need to know precisely what needs to be done, I'm more of a python dev than a react one.

@Enola-guy Can you please share your working code here?

I made a PR implementing this feature:

It extends the current SelectWidget to support optgroups at ui:options. e.g.:

  "selectWidgetOptions3": {
    "ui:options": {
      "optgroups": {
        "lipsum": [
          "foo"
        ],
        "dolorem": [
          "bar"
        ]
      }
    }
  }