Fixed #16311 -- Added a RelatedOnlyFieldListFilter class in admin.filters.

django/contrib/admin/__init__.py

@@ -6,7 +6,8 @@ from django.contrib.admin.options import (HORIZONTAL, VERTICAL,
     ModelAdmin, StackedInline, TabularInline)
 from django.contrib.admin.filters import (ListFilter, SimpleListFilter,
     FieldListFilter, BooleanFieldListFilter, RelatedFieldListFilter,
-    ChoicesFieldListFilter, DateFieldListFilter, AllValuesFieldListFilter)
+    ChoicesFieldListFilter, DateFieldListFilter, AllValuesFieldListFilter,
+    RelatedOnlyFieldListFilter)
 from django.contrib.admin.sites import AdminSite, site
 from django.utils.module_loading import autodiscover_modules
 
@@ -15,7 +16,7 @@ __all__ = [
     "StackedInline", "TabularInline", "AdminSite", "site", "ListFilter",
     "SimpleListFilter", "FieldListFilter", "BooleanFieldListFilter",
     "RelatedFieldListFilter", "ChoicesFieldListFilter", "DateFieldListFilter",
-    "AllValuesFieldListFilter", "autodiscover",
+    "AllValuesFieldListFilter", "RelatedOnlyFieldListFilter", "autodiscover",
 ]
 
 

django/contrib/admin/filters.py

@@ -170,7 +170,7 @@ class RelatedFieldListFilter(FieldListFilter):
         self.lookup_kwarg_isnull = '%s__isnull' % field_path
         self.lookup_val = request.GET.get(self.lookup_kwarg)
         self.lookup_val_isnull = request.GET.get(self.lookup_kwarg_isnull)
-        self.lookup_choices = field.get_choices(include_blank=False)
+        self.lookup_choices = self.field_choices(field, request, model_admin)
         super(RelatedFieldListFilter, self).__init__(
             field, request, params, model, model_admin, field_path)
         if hasattr(field, 'verbose_name'):
@@ -191,6 +191,9 @@ class RelatedFieldListFilter(FieldListFilter):
     def expected_parameters(self):
         return [self.lookup_kwarg, self.lookup_kwarg_isnull]
 
+    def field_choices(self, field, request, model_admin):
+        return field.get_choices(include_blank=False)
+
     def choices(self, cl):
         from django.contrib.admin.views.main import EMPTY_CHANGELIST_VALUE
         yield {
@@ -410,3 +413,9 @@ class AllValuesFieldListFilter(FieldListFilter):
             }
 
 FieldListFilter.register(lambda f: True, AllValuesFieldListFilter)
+
+
+class RelatedOnlyFieldListFilter(RelatedFieldListFilter):
+    def field_choices(self, field, request, model_admin):
+        limit_choices_to = {'pk__in': set(model_admin.get_queryset(request).values_list(field.name, flat=True))}
+        return field.get_choices(include_blank=False, limit_choices_to=limit_choices_to)

django/db/models/fields/__init__.py

@@ -726,7 +726,7 @@ class Field(RegisterLookupMixin):
     def get_validator_unique_lookup_type(self):
         return '%s__exact' % self.name
 
-    def get_choices(self, include_blank=True, blank_choice=BLANK_CHOICE_DASH):
+    def get_choices(self, include_blank=True, blank_choice=BLANK_CHOICE_DASH, limit_choices_to=None):
         """Returns choices with a default blank choices included, for use
         as SelectField choices for this field."""
         blank_defined = False
@@ -743,15 +743,16 @@ class Field(RegisterLookupMixin):
         if self.choices:
             return first_choice + choices
         rel_model = self.rel.to
+        limit_choices_to = limit_choices_to or self.get_limit_choices_to()
         if hasattr(self.rel, 'get_related_field'):
             lst = [(getattr(x, self.rel.get_related_field().attname),
                    smart_text(x))
                    for x in rel_model._default_manager.complex_filter(
-                       self.get_limit_choices_to())]
+                       limit_choices_to)]
         else:
             lst = [(x._get_pk_val(), smart_text(x))
                    for x in rel_model._default_manager.complex_filter(
-                       self.get_limit_choices_to())]
+                       limit_choices_to)]
         return first_choice + lst
 
     def get_choices_default(self):