[1.6.x] Fixed #21129 -- Prevented admin filter params modifications from throwing an exception.

Thanks Tuttle for the report.

Backport of 5381317fe3 from master

1 files changed, 12 insertions, 0 deletions

diff --git a/tests/modeladmin/tests.py b/tests/modeladmin/tests.py
index 805b57c070..ffc6219ebb 100644
--- a/tests/modeladmin/tests.py
+++ b/tests/modeladmin/tests.py
@@ -88,6 +88,18 @@ class ModelAdminTests(TestCase):
         form = ma.get_formset(None).form
         self.assertEqual(form._meta.fields, ['day', 'transport'])
 
+    def test_lookup_allowed_allows_nonexistent_lookup(self):
+        """
+        Ensure that a lookup_allowed allows a parameter
+        whose field lookup doesn't exist.
+        Refs #21129.
+        """
+        class BandAdmin(ModelAdmin):
+            fields = ['name']
+
+        ma = BandAdmin(Band, self.site)
+        self.assertTrue(ma.lookup_allowed('name__nonexistent', 'test_value'))
+
     def test_field_arguments(self):
         # If we specify the fields argument, fieldsets_add and fielsets_change should
         # just stick the fields into a formsets structure and return it.