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 (file)
index 0000000..e1e1442
--- /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 b9c890429e4f055ac607448b7d49536f6736da76..644e4aff63a8e2ab40bc0fbef9f51a11e9bb5283 100644 (file)
--- 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 eed918572895cedd066a9653d91cdd6f755be8bf..bc36ee9624fd68b60544f0c0ffd2b84df3227af0 100644 (file)
--- 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"))