gistfile1.py

class ModuleAdmin(admin.ModelAdmin):
    class ParentFilter(SimpleListFilter):
        title = _('Parent')
        parameter_name = 'parent'

        def lookups(self, request, model_admin):
            return [(m.id, m.name) for m in Module.objects.filter(parent__isnull=True).order_by('name')] + [('Null', 'Null')]

        def queryset(self, request, queryset):
            if self.value():
                if self.value() == 'Null':
                    return queryset.filter(parent__isnull=True)
                return queryset.filter(parent_id=self.value())


    class ModuleForm(forms.ModelForm):
        parent = forms.ModelChoiceField(queryset=Module.objects.filter(parent__isnull=True).order_by('name'),
                                        required=False)


    list_display = ('name', 'slug', 'parent', 'loan_type', 'type', 'is_active', 'get_app')
    list_filter = ('type', 'is_active', 'app', ParentFilter)
    search_fields = ('name', 'slug')
    prepopulated_fields = {'slug': ('name',)}
    ordering = ('loan_type', 'parent')
    form = ModuleForm