django admin manytomany field list_edit

manytomany_field_list_edit.py

"""
base https://gist.github.com/jdklub/9261959

usage:
@admin.register(XxxModel)
class XxxModelAdmin(ModelMultipleListEdit, admin.ModelAdmin):
    m_list_editable={
        "field":  {
            "queryset": field_queryset,
            "index": -1         # list_display index;   insert if index exists else  append
        }
    }

"""
from django import forms
from django.forms.utils import flatatt
from django.utils.safestring import mark_safe

__all__ = ['ModelMultipleListEdit']


class StyleableCheckboxSelectMultiple(forms.CheckboxSelectMultiple):
    def __init__(self, attrs=None, ul_attrs=None):
        self.ul_attrs = ul_attrs
        super().__init__(attrs)

    def render(self, *args, **kwargs):
        html = super().render(*args, **kwargs)
        final_attrs = self.build_attrs(self.ul_attrs)
        return mark_safe(html.replace('<ul>', '<ul%s>' % flatatt(final_attrs)))


class ModelMultipleListEdit:
    """
    m_list_editable={
        "field":  {
            "queryset": field_queryset,
            "index": -1         # list_display index,   insert if index exist else  append
        }
    }
    """
    m_list_editable = None

    def get_changelist_form(self, request, **kwargs):
        if not self.m_list_editable:
            return super().get_changelist_form(request, **kwargs)

        # dynamic create Form
        cls_dict = {}
        for field, v in self.m_list_editable.items():
            queryset = v['queryset']
            # dynamic create ManyToManyField form field
            cls_dict[field] = forms.ModelMultipleChoiceField(queryset=queryset, widget=StyleableCheckboxSelectMultiple(ul_attrs={"style": "height:80px; overflow-y:scroll;"}), required=False)

        cls = type('CloudAppForm', (forms.ModelForm,), cls_dict)
        return cls

    def get_changelist_instance(self, request):
        changeList = super().get_changelist_instance(request)
        if not self.m_list_editable:
            return changeList
        # injection ManyToManyField to list_display list_editable ;
        # use to  skip  ManyToManyField check;
        list_display = list(self.list_display)
        list_editable = list(self.list_editable)
        for field, v in self.m_list_editable.items():  # key
            if field not in list_display:

                if 'index' in v:  # 0 is valid value
                    list_display.insert(int(v['index']), field)
                else:
                    list_display.append(field)

            if field not in list_editable:
                list_editable.append(field)

        self.list_display = list_display
        self.list_editable = tuple(list_editable)

        # fix first request display
        changeList.list_display = list_display
        if changeList.is_popup:
            changeList.list_editable = ()
        else:
            changeList.list_editable = list_editable
        # fix first request display

        return changeList