[1.7.x] Fixed #22648 -- Transform.output_type should respect overridden custom_lookup and custom_transform.

Previously, class lookups from the output_type would be used, but any
changes to custom_lookup or custom_transform would be ignored.

Backport of a2dd618 from master

django/db/models/lookups.py

@@ -22,18 +22,20 @@ class RegisterLookupMixin(object):
         except AttributeError:
             # This class didn't have any class_lookups
             pass
-        if hasattr(self, 'output_type'):
-            return self.output_type.get_lookup(lookup_name)
         return None
 
     def get_lookup(self, lookup_name):
         found = self._get_lookup(lookup_name)
+        if found is None and hasattr(self, 'output_type'):
+            return self.output_type.get_lookup(lookup_name)
         if found is not None and not issubclass(found, Lookup):
             return None
         return found
 
     def get_transform(self, lookup_name):
         found = self._get_lookup(lookup_name)
+        if found is None and hasattr(self, 'output_type'):
+            return self.output_type.get_transform(lookup_name)
         if found is not None and not issubclass(found, Transform):
             return None
         return found

tests/custom_lookups/tests.py

@@ -89,6 +89,47 @@ class YearLte(models.lookups.LessThanOrEqual):
 YearTransform.register_lookup(YearLte)
 
 
+class SQLFunc(models.Lookup):
+    def __init__(self, name, *args, **kwargs):
+        super(SQLFunc, self).__init__(*args, **kwargs)
+        self.name = name
+
+    def as_sql(self, qn, connection):
+        return '%s()', [self.name]
+
+    @property
+    def output_type(self):
+        return CustomField()
+
+
+class SQLFuncFactory(object):
+
+    def __init__(self, name):
+        self.name = name
+
+    def __call__(self, *args, **kwargs):
+        return SQLFunc(self.name, *args, **kwargs)
+
+
+class CustomField(models.Field):
+
+    def get_lookup(self, lookup_name):
+        if lookup_name.startswith('lookupfunc_'):
+            key, name = lookup_name.split('_', 1)
+            return SQLFuncFactory(name)
+        return super(CustomField, self).get_lookup(lookup_name)
+
+    def get_transform(self, lookup_name):
+        if lookup_name.startswith('transformfunc_'):
+            key, name = lookup_name.split('_', 1)
+            return SQLFuncFactory(name)
+        return super(CustomField, self).get_transform(lookup_name)
+
+
+class CustomModel(models.Model):
+    field = CustomField()
+
+
 # We will register this class temporarily in the test method.
 
 
@@ -341,3 +382,22 @@ class LookupTransformCallOrderTests(TestCase):
 
         finally:
             models.DateField._unregister_lookup(TrackCallsYearTransform)
+
+
+class CustomisedMethodsTests(TestCase):
+
+    def test_overridden_get_lookup(self):
+        q = CustomModel.objects.filter(field__lookupfunc_monkeys=3)
+        self.assertIn('monkeys()', str(q.query))
+
+    def test_overridden_get_transform(self):
+        q = CustomModel.objects.filter(field__transformfunc_banana=3)
+        self.assertIn('banana()', str(q.query))
+
+    def test_overridden_get_lookup_chain(self):
+        q = CustomModel.objects.filter(field__transformfunc_banana__lookupfunc_elephants=3)
+        self.assertIn('elephants()', str(q.query))
+
+    def test_overridden_get_transform_chain(self):
+        q = CustomModel.objects.filter(field__transformfunc_banana__transformfunc_pear=3)
+        self.assertIn('pear()', str(q.query))