dial back the default "flatness" a bit, it will be there for joinedload and query.join(), but if

you're dealing with aliased() or with_polymorphic() you need to say "flat=True".  Just the one
flag though, "flat" implies "aliased".

5 files changed, 28 insertions, 19 deletions

diff --git a/lib/sqlalchemy/orm/mapper.py b/lib/sqlalchemy/orm/mapper.py
index 285d338de..7f14d83cb 100644
--- a/lib/sqlalchemy/orm/mapper.py
+++ b/lib/sqlalchemy/orm/mapper.py
@@ -1767,7 +1767,7 @@ class Mapper(_InspectionAttr):
         while stack:
             item = stack.popleft()
             descendants.append(item)
-            stack.extend(item._inheriting_mappers)
+            stack.extend(sorted(item._inheriting_mappers, key=lambda m: m.class_.__name__))
         return util.WeakSequence(descendants)
 
     def polymorphic_iterator(self):
diff --git a/lib/sqlalchemy/orm/query.py b/lib/sqlalchemy/orm/query.py
index d251f983f..54f5d7393 100644
--- a/lib/sqlalchemy/orm/query.py
+++ b/lib/sqlalchemy/orm/query.py
@@ -1897,7 +1897,7 @@ class Query(object):
                             )
 
         if not need_adapter and (create_aliases or aliased_entity):
-            right = aliased(right)
+            right = aliased(right, flat=True)
             need_adapter = True
 
         # if an alias() of the right side was generated here,
diff --git a/lib/sqlalchemy/orm/strategies.py b/lib/sqlalchemy/orm/strategies.py
index cabfb35b9..6394003b3 100644
--- a/lib/sqlalchemy/orm/strategies.py
+++ b/lib/sqlalchemy/orm/strategies.py
@@ -1060,6 +1060,14 @@ class JoinedLoader(AbstractRelationshipLoader):
                 column_collection=add_to_collection,
                 allow_innerjoin=allow_innerjoin)
 
+        if with_poly_info is not None and \
+            None in set(context.secondary_columns):
+            raise sa_exc.InvalidRequestError(
+                    "Detected unaliased columns when generating joined "
+                    "load.  Make sure to use aliased=True or flat=True "
+                    "when using joined loading with with_polymorphic()."
+                )
+
     def _get_user_defined_adapter(self, context, entity,
                                 path, adapter, user_defined_adapter):
 
@@ -1089,6 +1097,7 @@ class JoinedLoader(AbstractRelationshipLoader):
             to_adapt = with_poly_info.entity
         else:
             to_adapt = orm_util.AliasedClass(self.mapper,
+                                flat=True,
                                 use_mapper_path=True)
         clauses = orm_util.ORMAdapter(
                     to_adapt,
@@ -1415,8 +1424,7 @@ class LoadEagerFromAliasOption(PropertyOption):
                                                 "path_with_polymorphic")
                 adapter = orm_util.ORMAdapter(
                             with_poly_info.entity,
-                            equivalents=prop.mapper._equivalent_columns,
-                            adapt_required=True)
+                            equivalents=prop.mapper._equivalent_columns)
             else:
                 adapter = query._polymorphic_adapters.get(prop.mapper, None)
             paths[-1].set(query._attributes,
diff --git a/lib/sqlalchemy/orm/util.py b/lib/sqlalchemy/orm/util.py
index c21e7eace..7ac3ac96a 100644
--- a/lib/sqlalchemy/orm/util.py
+++ b/lib/sqlalchemy/orm/util.py
@@ -223,8 +223,8 @@ class ORMAdapter(sql_util.ColumnAdapter):
     and the AliasedClass if any is referenced.
 
     """
-    def __init__(self, entity, equivalents=None,
-                            chain_to=None, adapt_required=False):
+    def __init__(self, entity, equivalents=None, adapt_required=False,
+                            chain_to=None):
         info = inspection.inspect(entity)
 
         self.mapper = info.mapper
@@ -493,7 +493,7 @@ class AliasedClass(object):
     """
     def __init__(self, cls, alias=None,
                             name=None,
-                            flat=True,
+                            flat=False,
                             adapt_on_names=False,
                             #  TODO: None for default here?
                             with_polymorphic_mappers=(),
@@ -502,7 +502,8 @@ class AliasedClass(object):
                             use_mapper_path=False):
         mapper = _class_to_mapper(cls)
         if alias is None:
-            alias = mapper._with_polymorphic_selectable.alias(name=name, flat=flat)
+            alias = mapper._with_polymorphic_selectable.alias(
+                                            name=name, flat=flat)
         self._aliased_insp = AliasedInsp(
             self,
             mapper,
@@ -701,7 +702,7 @@ inspection._inspects(AliasedClass)(lambda target: target._aliased_insp)
 inspection._inspects(AliasedInsp)(lambda target: target)
 
 
-def aliased(element, alias=None, name=None, adapt_on_names=False):
+def aliased(element, alias=None, name=None, flat=False, adapt_on_names=False):
     """Produce an alias of the given element, usually an :class:`.AliasedClass`
     instance.
 
@@ -775,13 +776,14 @@ def aliased(element, alias=None, name=None, adapt_on_names=False):
             raise sa_exc.ArgumentError(
                 "adapt_on_names only applies to ORM elements"
             )
-        return element.alias(name)
+        return element.alias(name, flat=flat)
     else:
-        return AliasedClass(element, alias=alias,
+        return AliasedClass(element, alias=alias, flat=flat,
                     name=name, adapt_on_names=adapt_on_names)
 
 
 def with_polymorphic(base, classes, selectable=False,
+                        flat=False,
                         polymorphic_on=None, aliased=False,
                         innerjoin=False, _use_mapper_path=False):
     """Produce an :class:`.AliasedClass` construct which specifies
@@ -837,8 +839,8 @@ def with_polymorphic(base, classes, selectable=False,
     mappers, selectable = primary_mapper.\
                     _with_polymorphic_args(classes, selectable,
                                 innerjoin=innerjoin)
-    if aliased:
-        selectable = selectable.alias(flat=True)
+    if aliased or flat:
+        selectable = selectable.alias(flat=flat)
     return AliasedClass(base,
                 selectable,
                 with_polymorphic_mappers=mappers,
diff --git a/lib/sqlalchemy/sql/util.py b/lib/sqlalchemy/sql/util.py
index 6f4d27e1b..4422705cd 100644
--- a/lib/sqlalchemy/sql/util.py
+++ b/lib/sqlalchemy/sql/util.py
@@ -905,12 +905,11 @@ class ColumnAdapter(ClauseAdapter):
             if isinstance(c, expression.Label):
                 c = c.label(None)
 
-        # adapt_required indicates that if we got the same column
-        # back which we put in (i.e. it passed through),
-        # it's not correct.  this is used by eagerloading which
-        # knows that all columns and expressions need to be adapted
-        # to a result row, and a "passthrough" is definitely targeting
-        # the wrong column.
+        # adapt_required used by eager loading to indicate that
+        # we don't trust a result row column that is not translated.
+        # this is to prevent a column from being interpreted as that
+        # of the child row in a self-referential scenario, see
+        # inheritance/test_basic.py->EagerTargetingTest.test_adapt_stringency
         if self.adapt_required and c is col:
             return None