From: Mike Bayer <mike_mp@zzzcomputing.com>
Date: Sun, 27 Sep 2020 15:44:58 +0000 (-0400)
Subject: Accommodate for same base class multiple times in inherits list
X-Git-Tag: rel_1_4_0b1~73^2
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=17dd7fce6164794f6fd75a9351061f109e3360b1;p=thirdparty%2Fsqlalchemy%2Fsqlalchemy.git

Accommodate for same base class multiple times in inherits list

Improved declarative inheritance scanning to not get tripped up when the
same base class appears multiple times in the base inheritance list.

Fixes: #4699
Change-Id: I932e735cd2e2c1efa935936c84219924225d10f1
---

diff --git a/doc/build/changelog/unreleased_14/4699.rst b/doc/build/changelog/unreleased_14/4699.rst
new file mode 100644
index 0000000000..e1e1442cf2
--- /dev/null
+++ b/doc/build/changelog/unreleased_14/4699.rst
@@ -0,0 +1,7 @@
+.. change::
+    :tags: bug, orm
+    :tickets: 4699
+
+    Improved declarative inheritance scanning to not get tripped up when the
+    same base class appears multiple times in the base inheritance list.
+
diff --git a/lib/sqlalchemy/orm/decl_base.py b/lib/sqlalchemy/orm/decl_base.py
index b9c890429e..644e4aff63 100644
--- a/lib/sqlalchemy/orm/decl_base.py
+++ b/lib/sqlalchemy/orm/decl_base.py
@@ -677,7 +677,8 @@ class _ClassScanMapperConfig(_MapperConfig):
                 ) is not None and not _get_immediate_cls_attr(
                     c, "_sa_decl_prepare_nocascade", strict=True
                 ):
-                    inherits_search.append(c)
+                    if c not in inherits_search:
+                        inherits_search.append(c)
 
             if inherits_search:
                 if len(inherits_search) > 1:
diff --git a/test/orm/declarative/test_mixin.py b/test/orm/declarative/test_mixin.py
index eed9185728..bc36ee9624 100644
--- a/test/orm/declarative/test_mixin.py
+++ b/test/orm/declarative/test_mixin.py
@@ -218,6 +218,31 @@ class DeclarativeMixinTest(DeclarativeTestBase):
         eq_(MyModelA.__table__.c.foo.type.__class__, String)
         eq_(MyModelB.__table__.c.foo.type.__class__, Integer)
 
+    def test_same_base_multiple_times(self):
+        class User(Base):
+            __tablename__ = "user"
+
+            id = Column(Integer, primary_key=True)
+            name = Column(String)
+            surname = Column(String)
+
+        class SpecialUser(User):
+            __abstract__ = True
+
+        class ConvenienceStuff(User):
+            __abstract__ = True
+
+            def fullname(self):
+                return self.name + " " + self.surname
+
+        class Manager(SpecialUser, ConvenienceStuff, User):
+            __tablename__ = "manager"
+
+            id = Column(Integer, ForeignKey("user.id"), primary_key=True)
+            title = Column(String)
+
+        eq_(Manager.__table__.name, "manager")
+
     def test_not_allowed(self):
         class MyMixin:
             foo = Column(Integer, ForeignKey("bar.id"))