from django import forms
from django.contrib import admin
from django.contrib.admin.widgets import FilteredSelectMultiple
from django.contrib.auth.admin import GroupAdmin
from django.contrib.auth.models import Group

class GroupAdminForm(forms.ModelForm):
    users = forms.ModelMultipleChoiceField(queryset=AGLUser.objects.all(),
                                           widget=FilteredSelectMultiple('Users', False),
                                           required=False)
    class Meta:
        model = Group
        
    def __init__(self, *args, **kwargs):
        instance = kwargs.get('instance', None)
        if instance is not None:
            initial = kwargs.get('initial', {})
            initial['users'] = instance.user_set.all()
            kwargs['initial'] = initial
        super(GroupChangeForm, self).__init__(*args, **kwargs)
        
    def save(self, commit=True):
        group = super(GroupChangeForm, self).save(commit=commit)
        
        if commit:
            group.user_set = self.cleaned_data['users']
        else:
            old_save_m2m = self.save_m2m
            def new_save_m2m():
                old_save_m2m()
                group.user_set = self.cleaned_data['users']
            self.save_m2m = new_save_m2m
        return group

class MyGroupAdmin(GroupAdmin):
    form = GroupAdminForm

site = admin.AdminSite()
site.register(Group, MyGroupAdmin)