Is multi choice django admin filters possible..?

Question

Suppose if there is a model named 'Cities' and at admin side there is a filter 'city_name' to filter model based on city names. By default django only allows to choose one city name from the django admin filter. But I need to choose multipile city names in django admin filter.How can i do that.??

Answer 1

You can use a slightly modified version of built in AllValuesFieldListFilter:

from django.contrib import admin
from django.contrib.admin.utils import reverse_field_path
from django.utils.translation import gettext_lazy as _

class MultiSelectFieldListFilter(admin.FieldListFilter):
    def __init__(self, field, request, params, model, model_admin, field_path):
        self.lookup_kwarg = field_path + '__in'
        self.lookup_kwarg_isnull = field_path + '__isnull'

        super().__init__(field, request, params, model, model_admin, field_path)

        self.lookup_val = self.used_parameters.get(self.lookup_kwarg, [])
        if len(self.lookup_val) == 1 and self.lookup_val[0] == '':
            self.lookup_val = []
        self.lookup_val_isnull = self.used_parameters.get(self.lookup_kwarg_isnull)

        self.empty_value_display = model_admin.get_empty_value_display()
        parent_model, reverse_path = reverse_field_path(model, field_path)
        # Obey parent ModelAdmin queryset when deciding which options to show
        if model == parent_model:
            queryset = model_admin.get_queryset(request)
        else:
            queryset = parent_model._default_manager.all()
        self.lookup_choices = queryset.distinct().order_by(field.name).values_list(field.name, flat=True)

    def expected_parameters(self):
        return [self.lookup_kwarg, self.lookup_kwarg_isnull]

    def choices(self, changelist):
        yield {
            'selected': not self.lookup_val and self.lookup_val_isnull is None,
            'query_string': changelist.get_query_string(remove=[self.lookup_kwarg, self.lookup_kwarg_isnull]),
            'display': _('All'),
        }
        include_none = False
        for val in self.lookup_choices:
            if val is None:
                include_none = True
                continue
            val = str(val)

            if val in self.lookup_val:
                values = [v for v in self.lookup_val if v != val]
            else:
                values = self.lookup_val + [ val ]

            if values:
                yield {
                    'selected': val in self.lookup_val,
                    'query_string': changelist.get_query_string({self.lookup_kwarg: ','.join(values)}, [self.lookup_kwarg_isnull]),
                    'display': val,
                }
            else:
                yield {
                    'selected': val in self.lookup_val,
                    'query_string': changelist.get_query_string(remove=[self.lookup_kwarg]),
                    'display': val,
                }

        if include_none:
            yield {
                'selected': bool(self.lookup_val_isnull),
                'query_string': changelist.get_query_string({self.lookup_kwarg_isnull: 'True'}, [self.lookup_kwarg]),
                'display': self.empty_value_display,
            }

Escaping commas in values should be implemented too, but I didn't need it.

(Tested with Django 2.2.5)

Answer 2

You can use this new tool django-admin-multiple-choice-list-filter.