django admin filters cascading

Question

I've got a question - can Django Admin interface be customized in such a way, that it presents only those filter options that occur in the subset of data matching currently selected filters?

Say I have a db of three objects:

a.Foo = "One"
a.Bar = "Drink"

b.Foo = "One"
b.Bar = "Shot"

c.Foo = "Two"
c.Bar = "Shot"

And a django admin interface with filters on 'Foo' and 'Bar'. I want the following behavior:

If no filters are chosen, 'Foo' lists "One","Two"; 'Bar' lists "Drink", "Shot"
If 'Foo' filter is set to "One", 'Bar' lists both "Drink" and "Shot"
If 'Foo' filter is set to "Two", 'Bar' lists only "Shot"
If 'Bar' filter is set to "Shot", 'Foo' lists both "One" and "Two"
If 'Bar' filter is set to "Drink", 'Foo' lists only "One"

Cheers!

To be more specific - after reading some docs:

from django.contrib.admin import SimpleListFilter

class SomeFilter(SimpleListFilter):
  title = "Foo"
  parameter_name="Some"
  def lookups(self, request, model_admin):
    qs = model_admin.queryset(request)
    print qs.query
    return (('Foo', 'Bar'))
  def queryset(self, request, queryset):
    if (self.value()):
      return queryset.filter(Some=self.value())
    else:
      return queryset

What it does, however, is gets the 'queryset' as it would've been without other filters. How can I pass it through other filters?

I could theoretically parse the request and filter manually - but there surely needs to be a way to pipe all filters.

Added more information after some research - I can't quite figure out how to get the queryset after all other filters have piped through it. — qdot, Sep 03 '11 at 23:43

score 2 · Accepted Answer · answered Sep 07 '11 at 17:43

2

This kind of dynamic filtering really looks like faceting. While you may be able to achieve this result with a standard queryset, this will probably not be optimal. You may have more chance using a dedicated tool, like Solr.

Haystack has also a doc page on faceting.

answered Sep 07 '11 at 17:43

Thibault J

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haystack really sounds like a nice place to start drilling into.. good tip! – qdot Sep 07 '11 at 17:58

score 1 · Answer 2 · answered Nov 08 '13 at 02:25

in case anyone needs a lightweight solution, this one does a Country filter that is hidden when no Continent is selected in the filter and only offers those countries that exist in the selected Continent:

from django.utils.translation import ugettext_lazy as _
class ContinentCountryListFilter(admin.SimpleListFilter):
    # Human-readable title which will be displayed in the
    # right admin sidebar just above the filter options.
    title = _('country')

    # Parameter for the filter that will be used in the URL query.
    parameter_name = 'country__iso_code__exact'

    def lookups(self, request, model_admin):
        """
        Returns a list of tuples. The first element in each
        tuple is the coded value for the option that will
        appear in the URL query. The second element is the
        human-readable name for the option that will appear
        in the right sidebar.
        """

        continent = request.GET.get('country__continent__iso_code__exact', '')

        if continent:
            countries = models.Country.objects.filter(continent__iso_code__exact=continent)
        else:
            countries = models.Country.objects.none()

        return countries.values_list('iso_code', 'name')

    def queryset(self, request, queryset):
        """
        Returns the filtered queryset based on the value
        provided in the query string and retrievable via
        `self.value()`.
        """
        continent = request.GET.get('country__continent__iso_code__exact', '')

        # only apply filter if continent is set and country exists in continent
        if continent and models.Country.objects.filter(continent__iso_code__exact=continent, iso_code__exact=self.value()).count():
            return queryset.filter(country__iso_code__exact=self.value())

        return queryset

and then apply with:

list_filter = ('country__continent', ContinentCountryListFilter, )

django admin filters cascading

2 Answers2