[Django]-How to override the queryset giving the filters in list_filter?

Edit – this method has been pointed out to have issues, see below

You can do it like this:

Let’s say you have a model called Animal, which has a ForeignKey field to a model called Species. In a particular admin list, you want to allow only certain species to be shown in the animals filter choices.

First, specify a custom ListFilter called SpeciesFilter in the Animal’s ModelAdmin:

class AnimalAdmin(ModelAdmin):
    list_filter = (('species', SpeciesFilter),)

Then define the SpeciesFilter:

from django.contrib.admin.filters import RelatedFieldListFilter

class SpeciesFilter(RelatedFieldListFilter):
    def __init__(self, field, request, *args, **kwargs):
        """Get the species you want to limit it to.
        This could be determined by the request,
        But in this example we'll just specify an
        arbitrary species"""
        species = Species.objects.get(name='Tarantula')

        #Limit the choices on the field
        field.rel.limit_choices_to = {'species': species}

        #Let the RelatedFieldListFilter do its magic 
        super(SpeciesFilter, self).__init__(field, request, *args, **kwargs)

That should do it.

I found another method similar to @seddonym, but doesn’t mess with the caching. It is based on this Django code, but uses undocumented method field_choices, which can be subject to change in the future Django releases. The code for @seddonym’s case would be:

from django.contrib.admin.filters import RelatedFieldListFilter

class SpeciesFilter(RelatedFieldListFilter):
    def field_choices(self, field, request, model_admin):
        return field.get_choices(include_blank=False, limit_choices_to={'name': 'Tarantula'})

Or in my case the working code is:

from django.contrib.admin.filters import RelatedFieldListFilter

class UnitFilter(RelatedFieldListFilter):
    def field_choices(self, field, request, model_admin):
        return field.get_choices(include_blank=False, limit_choices_to={'pk__in': request.user.administrated_units.all()})

I had to create my lookup fields from db table. I created custom filter class as below and displaying only related values to logged in user and filter accordingly:

class ShiftFilter_Org(admin.SimpleListFilter):
title = 'Organisation'
parameter_name = 'org'

def lookups(self, request, model_admin):
"""Get the organisations you want to limit"""
    qs_org = Organisation.objects.filter(users=request.user)
    list_org = []
    for og in qs_org:
        list_org.append(
            (og.id, og.name)
        )
    return (
        sorted(list_org, key=lambda tp:tp[1])
    )

def queryset(self, request, queryset):
    if self.value():
        return queryset.filter(org=self.value())

For more visit Getting the most out of Django Admin filters

To use RelatedFieldListFilter like suggested in some answers, you need to pass a tuple to list_filter. Following the classes definition used in the original question, you would have:

class MyModelAdmin(admin.ModelAdmin): 
    class AnotherModelListFilter(admin.RelatedFieldListFilter):
        def field_choices(self, field, request, model_admin):
            ordering = self.field_admin_ordering(field, request, model_admin)
            return field.get_choices(
                include_blank=False,
                ordering=ordering,
                limit_choices_to=dict(n=<THE_VALUE_YOU_WANT>),
            )
    list_filter = (('somefield', AnotherModelListFilter),)