Adapt from "localparent" in joinedloader

Fixed bug involving joined eager loading against multiple entities
when polymorphic inheritance is also in use which would throw
"'NoneType' object has no attribute 'isa'".  The issue was introduced
by the fix for :ticket:`3611`.

Change-Id: I296ecda38c01ec8f69dcd843beaebed6949cecfa
Fixes: #3884

3 files changed, 86 insertions, 3 deletions

diff --git a/doc/build/changelog/changelog_10.rst b/doc/build/changelog/changelog_10.rst
index 4ae8a8fbb..aa3a4c7e6 100644
--- a/doc/build/changelog/changelog_10.rst
+++ b/doc/build/changelog/changelog_10.rst
@@ -16,6 +16,19 @@
         :start-line: 5
 
 .. changelog::
+    :version: 1.0.17
+
+    .. change::
+        :tags: bug, orm
+        :tickets: 3884
+        :versions: 1.1.5
+
+        Fixed bug involving joined eager loading against multiple entities
+        when polymorphic inheritance is also in use which would throw
+        "'NoneType' object has no attribute 'isa'".  The issue was introduced
+        by the fix for :ticket:`3611`.
+
+.. changelog::
     :version: 1.0.16
     :released: November 15, 2016
 
diff --git a/lib/sqlalchemy/orm/strategies.py b/lib/sqlalchemy/orm/strategies.py
index 33feab0dc..273ec1280 100644
--- a/lib/sqlalchemy/orm/strategies.py
+++ b/lib/sqlalchemy/orm/strategies.py
@@ -1368,8 +1368,8 @@ class JoinedLoader(AbstractRelationshipLoader):
                 # name on it.
                 efm = inspect(adapter.aliased_class).\
                     _entity_for_mapper(
-                        parentmapper
-                        if parentmapper.isa(self.parent) else self.parent)
+                        localparent
+                        if localparent.isa(self.parent) else self.parent)
 
                 # look for our attribute on the adapted entity, else fall back
                 # to our straight property
diff --git a/test/orm/inheritance/test_relationship.py b/test/orm/inheritance/test_relationship.py
index 46b934d7b..9f58896af 100644
--- a/test/orm/inheritance/test_relationship.py
+++ b/test/orm/inheritance/test_relationship.py
@@ -1,6 +1,6 @@
 from sqlalchemy.orm import create_session, relationship, mapper, \
     contains_eager, joinedload, subqueryload, subqueryload_all,\
-    Session, aliased, with_polymorphic, joinedload_all
+    Session, aliased, with_polymorphic, joinedload_all, backref
 
 from sqlalchemy import Integer, String, ForeignKey, select, func
 from sqlalchemy.engine import default
@@ -1934,3 +1934,73 @@ class SameNameOnJoined(fixtures.MappedTest):
         s.commit()
 
         eq_(s.query(B).count(), 0)
+
+
+class BetweenSubclassJoinWExtraJoinedLoad(
+        fixtures.DeclarativeMappedTest,
+        testing.AssertsCompiledSQL):
+    """test for [ticket:3884]"""
+
+    run_define_tables = None
+    __dialect__ = 'default'
+
+    @classmethod
+    def setup_classes(cls):
+        Base = cls.DeclarativeBasic
+
+        class Person(Base):
+            __tablename__ = 'people'
+            id = Column(Integer, primary_key=True)
+            discriminator = Column('type', String(50))
+            __mapper_args__ = {'polymorphic_on': discriminator}
+
+        class Manager(Person):
+            __tablename__ = 'managers'
+            __mapper_args__ = {'polymorphic_identity': 'manager'}
+            id = Column(Integer, ForeignKey('people.id'), primary_key=True)
+
+        class Engineer(Person):
+            __tablename__ = 'engineers'
+            __mapper_args__ = {'polymorphic_identity': 'engineer'}
+            id = Column(Integer, ForeignKey('people.id'), primary_key=True)
+            primary_language = Column(String(50))
+            manager_id = Column(Integer, ForeignKey('managers.id'))
+            manager = relationship(
+                Manager, primaryjoin=(Manager.id == manager_id))
+
+        class LastSeen(Base):
+            __tablename__ = 'seen'
+            id = Column(Integer, ForeignKey('people.id'), primary_key=True)
+            timestamp = Column(Integer)
+            taggable = relationship(
+                Person, primaryjoin=(Person.id == id),
+                backref=backref("last_seen", lazy=False))
+
+    def test_query(self):
+        Engineer, Manager = self.classes("Engineer", "Manager")
+
+        sess = Session()
+
+        # eager join is both from Enginer->LastSeen as well as
+        # Manager->LastSeen.  In the case of Manager->LastSeen,
+        # Manager is internally aliased, and comes to JoinedEagerLoader
+        # with no "parent" entity but an adapter.
+        q = sess.query(Engineer, Manager).join(Engineer.manager)
+        self.assert_compile(
+            q,
+            "SELECT people.type AS people_type, engineers.id AS engineers_id, "
+            "people.id AS people_id, "
+            "engineers.primary_language AS engineers_primary_language, "
+            "engineers.manager_id AS engineers_manager_id, "
+            "people_1.type AS people_1_type, managers_1.id AS managers_1_id, "
+            "people_1.id AS people_1_id, seen_1.id AS seen_1_id, "
+            "seen_1.timestamp AS seen_1_timestamp, seen_2.id AS seen_2_id, "
+            "seen_2.timestamp AS seen_2_timestamp "
+            "FROM people JOIN engineers ON people.id = engineers.id "
+            "JOIN (people AS people_1 JOIN managers AS managers_1 "
+            "ON people_1.id = managers_1.id) "
+            "ON managers_1.id = engineers.manager_id LEFT OUTER JOIN "
+            "seen AS seen_1 ON people.id = seen_1.id LEFT OUTER JOIN "
+            "seen AS seen_2 ON people_1.id = seen_2.id"
+        )
+