Select2 Django admin widget for ArrayFields

widgets.py

class ArrayTagWidget(Select2TagWidget):

    def build_attrs(self, *args, **kwargs):
        self.attrs.setdefault('data-token-separators', [])
        self.attrs.setdefault('data-width', '500px')
        self.attrs.setdefault('data-tags', 'true')
        return super().build_attrs(*args, **kwargs)

    def value_from_datadict(self, data, files, name):
        values = super().value_from_datadict(data, files, name)
        return ','.join([x.replace(',', '|') for x in values])

    def optgroups(self, name, value, attrs=None):
        values = [x.replace('|', ',') for x in value[0].split(',')] if value[0] else []
        selected = {*values}
        subgroup = [self.create_option(name, v, v, selected, i) for i, v in enumerate(values)]
        return [(None, subgroup, 0)]

Updated to support Django 1.11 after some breaking changes in the widget rendering API