Fixed #13640: Avoid generating an exception when a model has an attri…

…bute named 'evaluate'. Thanks LukaszKorzybski and tobias.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@17093 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/db/models/sql/query.py

@@ -14,6 +14,7 @@
 from django.utils.tree import Node
 from django.db import connections, DEFAULT_DB_ALIAS
 from django.db.models import signals
+from django.db.models.expressions import ExpressionNode
 from django.db.models.fields import FieldDoesNotExist
 from django.db.models.query_utils import InvalidQuery
 from django.db.models.sql import aggregates as base_aggregates_module
@@ -1064,7 +1065,7 @@ def add_filter(self, filter_expr, connector=AND, negate=False, trim=False,
             value = True
         elif callable(value):
             value = value()
-        elif hasattr(value, 'evaluate'):
+        elif isinstance(value, ExpressionNode):
             # If value is a query expression, evaluate it
             value = SQLEvaluator(value, self)
             having_clause = value.contains_aggregate

tests/regressiontests/model_regress/tests.py

@@ -164,8 +164,23 @@ def test_timezones(self):
             1
         )
 
+
 class ModelValidationTest(TestCase):
     def test_pk_validation(self):
         one = NonAutoPK.objects.create(name="one")
         again = NonAutoPK(name="one")
         self.assertRaises(ValidationError, again.validate_unique)
+
+
+class EvaluateMethodTest(TestCase):
+    """
+    Regression test for #13640: cannot filter by objects with 'evaluate' attr
+    """
+
+    def test_model_with_evaluate_method(self):
+        """
+        Ensures that you can filter by objects that have an 'evaluate' attr
+        """
+        dept = Department.objects.create(pk=1, name='abc')
+        dept.evaluate = 'abc'
+        Worker.objects.filter(department=dept)