From: Mike Bayer <mike_mp@zzzcomputing.com>
Date: Wed, 19 Oct 2022 01:01:05 +0000 (-0400)
Subject: de-optionalize union types to support Optional for m2o
X-Git-Tag: rel_2_0_0b2~7^2
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=257002227b811c85c7887236321d9965455889bc;p=thirdparty%2Fsqlalchemy%2Fsqlalchemy.git

de-optionalize union types to support Optional for m2o

Fixed bug in new ORM typed declarative mappings where we did not include
the ability to use ``Optional[]`` in the type annotation for a many-to-one
relationship, even though this is common.

Fixes: #8668
Change-Id: Idaf0846e49cc12095394b99ad6fe678735cf9242
---

diff --git a/doc/build/changelog/unreleased_20/8668.rst b/doc/build/changelog/unreleased_20/8668.rst
new file mode 100644
index 0000000000..3dab4663fd
--- /dev/null
+++ b/doc/build/changelog/unreleased_20/8668.rst
@@ -0,0 +1,7 @@
+.. change::
+    :tags: bug, orm
+    :tickets: 8668
+
+    Fixed bug in new ORM typed declarative mappings where we did not include
+    the ability to use ``Optional[]`` in the type annotation for a many-to-one
+    relationship, even though this is common.
diff --git a/lib/sqlalchemy/orm/relationships.py b/lib/sqlalchemy/orm/relationships.py
index 86a0f82c56..81c26d3722 100644
--- a/lib/sqlalchemy/orm/relationships.py
+++ b/lib/sqlalchemy/orm/relationships.py
@@ -86,6 +86,7 @@ from ..sql.util import ClauseAdapter
 from ..sql.util import join_condition
 from ..sql.util import selectables_overlap
 from ..sql.util import visit_binary_product
+from ..util.typing import de_optionalize_union_types
 from ..util.typing import Literal
 
 if typing.TYPE_CHECKING:
@@ -1742,18 +1743,21 @@ class RelationshipProperty(
             self.lazy = "dynamic"
             self.strategy_key = (("lazy", self.lazy),)
 
-        if hasattr(argument, "__origin__"):
+        argument = de_optionalize_union_types(argument)
 
-            collection_class = argument.__origin__  # type: ignore
-            if issubclass(collection_class, abc.Collection):
+        if hasattr(argument, "__origin__"):
+            arg_origin = argument.__origin__  # type: ignore
+            if isinstance(arg_origin, type) and issubclass(
+                arg_origin, abc.Collection
+            ):
                 if self.collection_class is None:
-                    self.collection_class = collection_class
+                    self.collection_class = arg_origin
             elif not is_write_only and not is_dynamic:
                 self.uselist = False
 
             if argument.__args__:  # type: ignore
-                if issubclass(
-                    argument.__origin__, typing.Mapping  # type: ignore
+                if isinstance(arg_origin, type) and issubclass(
+                    arg_origin, typing.Mapping  # type: ignore
                 ):
                     type_arg = argument.__args__[-1]  # type: ignore
                 else:
diff --git a/test/orm/declarative/test_dc_transforms.py b/test/orm/declarative/test_dc_transforms.py
index ae1f9b35e1..bff9482ec5 100644
--- a/test/orm/declarative/test_dc_transforms.py
+++ b/test/orm/declarative/test_dc_transforms.py
@@ -321,7 +321,7 @@ class DCTransformsTest(AssertsCompiledSQL, fixtures.TestBase):
             id: Mapped[intpk] = mapped_column(init=False)
             email_address: Mapped[str]
             user_id: Mapped[user_fk] = mapped_column(init=False)
-            user: Mapped["User"] = relationship(
+            user: Mapped[Optional["User"]] = relationship(
                 back_populates="addresses", default=None
             )
 
diff --git a/test/orm/declarative/test_typed_mapping.py b/test/orm/declarative/test_typed_mapping.py
index b64694fc59..ae8e9d746b 100644
--- a/test/orm/declarative/test_typed_mapping.py
+++ b/test/orm/declarative/test_typed_mapping.py
@@ -1236,7 +1236,8 @@ class RelationshipLHSTest(fixtures.TestBase, testing.AssertsCompiledSQL):
             select(A).join(A.bs), "SELECT a.id FROM a JOIN b ON a.id = b.a_id"
         )
 
-    def test_basic_bidirectional(self, decl_base):
+    @testing.combinations(True, False, argnames="optional_on_m2o")
+    def test_basic_bidirectional(self, decl_base, optional_on_m2o):
         class A(decl_base):
             __tablename__ = "a"
 
@@ -1251,9 +1252,14 @@ class RelationshipLHSTest(fixtures.TestBase, testing.AssertsCompiledSQL):
             id: Mapped[int] = mapped_column(Integer, primary_key=True)
             a_id: Mapped[int] = mapped_column(ForeignKey("a.id"))
 
-            a: Mapped["A"] = relationship(
-                back_populates="bs", primaryjoin=a_id == A.id
-            )
+            if optional_on_m2o:
+                a: Mapped[Optional["A"]] = relationship(
+                    back_populates="bs", primaryjoin=a_id == A.id
+                )
+            else:
+                a: Mapped["A"] = relationship(
+                    back_populates="bs", primaryjoin=a_id == A.id
+                )
 
         a1 = A(data="data")
         b1 = B()