lint: use type narrowing for orm.object_session() (#17582)

Since `object_session(...)` can return `None`, we need to help mypy have
confidence that the session is indeed there.

One way to narrow the type is to assert that it's not `None`, and
therefore should not alert about `union-attr` problems.

Includes a couple of renames, and variable extraction where relevant.

Signed-off-by: Mike Fiedler <miketheman@gmail.com>

tests/unit/utils/db/test_orm.py

@@ -0,0 +1,31 @@
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import pytest
+
+from sqlalchemy.orm import object_session
+
+from warehouse.db import Model
+from warehouse.utils.db.orm import NoSessionError, orm_session_from_obj
+
+
+def test_orm_session_from_obj_raises_with_no_session():
+
+    class FakeObject(Model):
+        __tablename__ = "fake_object"
+
+    obj = FakeObject()
+    # Confirm that the object does not have a session with the built-in
+    assert object_session(obj) is None
+
+    with pytest.raises(NoSessionError):
+        orm_session_from_obj(obj)

warehouse/accounts/models.py

@@ -40,6 +40,7 @@
 from warehouse.observations.models import HasObservations, HasObservers, ObservationKind
 from warehouse.sitemap.models import SitemapMixin
 from warehouse.utils.attrs import make_repr
+from warehouse.utils.db import orm_session_from_obj
 from warehouse.utils.db.types import TZDateTime, bool_false, datetime_now
 
 if TYPE_CHECKING:
@@ -236,7 +237,7 @@ def has_primary_verified_email(self):
 
     @property
     def recent_events(self):
-        session = orm.object_session(self)
+        session = orm_session_from_obj(self)
         last_ninety = datetime.datetime.now() - datetime.timedelta(days=90)
         return (
             session.query(User.Event)

warehouse/cache/origin/__init__.py

@@ -16,11 +16,10 @@
 
 from itertools import chain
 
-from sqlalchemy.orm.session import Session
-
 from warehouse import db
 from warehouse.cache.origin.derivers import html_cache_deriver
 from warehouse.cache.origin.interfaces import IOriginCache
+from warehouse.utils.db import orm_session_from_obj
 
 
 @db.listens_for(db.Session, "after_flush")
@@ -139,7 +138,7 @@ def register_origin_cache_keys(config, klass, cache_keys=None, purge_keys=None):
 
 def receive_set(attribute, config, target):
     cache_keys = config.registry["cache_keys"]
-    session = Session.object_session(target)
+    session = orm_session_from_obj(target)
     purges = session.info.setdefault("warehouse.cache.origin.purges", set())
     key_maker = cache_keys[attribute]
     keys = key_maker(target).purge

warehouse/email/ses/models.py

@@ -20,10 +20,10 @@
 from sqlalchemy.dialects.postgresql import JSONB, UUID as PG_UUID
 from sqlalchemy.ext.mutable import MutableDict
 from sqlalchemy.orm import Mapped, mapped_column
-from sqlalchemy.orm.session import object_session
 
 from warehouse import db
 from warehouse.accounts.models import Email as EmailAddress, UnverifyReasons
+from warehouse.utils.db import orm_session_from_obj
 from warehouse.utils.db.types import bool_false, datetime_now
 
 MAX_TRANSIENT_BOUNCES = 5
@@ -217,9 +217,9 @@ def _get_email(self):
         if self._email_message.missing:
             return
 
-        db = object_session(self._email_message)
+        session = orm_session_from_obj(self._email_message)
         email = (
-            db.query(EmailAddress)
+            session.query(EmailAddress)
             .filter(EmailAddress.email == self._email_message.to)
             .first()
         )

warehouse/legacy/api/xmlrpc/cache/__init__.py

@@ -14,7 +14,6 @@
 
 from pyramid.exceptions import ConfigurationError
 from sqlalchemy.orm.base import NO_VALUE
-from sqlalchemy.orm.session import Session
 from urllib3.util import parse_url
 
 from warehouse import db
@@ -23,6 +22,7 @@
 from warehouse.legacy.api.xmlrpc.cache.fncache import RedisLru
 from warehouse.legacy.api.xmlrpc.cache.interfaces import IXMLRPCCache
 from warehouse.legacy.api.xmlrpc.cache.services import NullXMLRPCCache, RedisXMLRPCCache
+from warehouse.utils.db import orm_session_from_obj
 
 __all__ = ["RedisLru"]
 
@@ -32,7 +32,7 @@
 
 def receive_set(attribute, config, target):
     cache_keys = config.registry["cache_keys"]
-    session = Session.object_session(target)
+    session = orm_session_from_obj(target)
     purges = session.info.setdefault("warehouse.legacy.api.xmlrpc.cache.purges", set())
     key_maker = cache_keys[attribute]
     keys = key_maker(target).purge

warehouse/organizations/models.py

@@ -43,6 +43,7 @@
 from warehouse.authnz import Permissions
 from warehouse.events.models import HasEvents
 from warehouse.utils.attrs import make_repr
+from warehouse.utils.db import orm_session_from_obj
 from warehouse.utils.db.types import TZDateTime, bool_false, datetime_now
 
 if typing.TYPE_CHECKING:
@@ -332,22 +333,17 @@ class Organization(OrganizationMixin, HasEvents, db.Model):
     @property
     def owners(self):
         """Return all users who are owners of the organization."""
+        session = orm_session_from_obj(self)
         owner_roles = (
-            orm.object_session(self)
-            .query(User.id)
+            session.query(User.id)
             .join(OrganizationRole.user)
             .filter(
                 OrganizationRole.role_name == OrganizationRoleType.Owner,
                 OrganizationRole.organization == self,
             )
             .subquery()
         )
-        return (
-            orm.object_session(self)
-            .query(User)
-            .join(owner_roles, User.id == owner_roles.c.id)
-            .all()
-        )
+        return session.query(User).join(owner_roles, User.id == owner_roles.c.id).all()
 
     def record_event(self, *, tag, request: Request = None, additional=None):
         """Record organization name in events in case organization is ever deleted."""
@@ -358,7 +354,7 @@ def record_event(self, *, tag, request: Request = None, additional=None):
         )
 
     def __acl__(self):
-        session = orm.object_session(self)
+        session = orm_session_from_obj(self)
 
         acls = [
             (

warehouse/packaging/models.py

@@ -79,6 +79,7 @@
 from warehouse.sitemap.models import SitemapMixin
 from warehouse.utils import dotted_navigator, wheel
 from warehouse.utils.attrs import make_repr
+from warehouse.utils.db import orm_session_from_obj
 from warehouse.utils.db.types import bool_false, bool_true, datetime_now
 
 if typing.TYPE_CHECKING:
@@ -257,7 +258,7 @@ class Project(SitemapMixin, HasEvents, HasObservations, db.Model):
     )
 
     def __getitem__(self, version):
-        session = orm.object_session(self)
+        session = orm_session_from_obj(self)
         canonical_version = packaging.utils.canonicalize_version(version)
 
         try:
@@ -288,7 +289,7 @@ def __getitem__(self, version):
             raise KeyError from None
 
     def __acl__(self):
-        session = orm.object_session(self)
+        session = orm_session_from_obj(self)
         acls = [
             # TODO: Similar to `warehouse.accounts.models.User.__acl__`, we express the
             #       permissions here in terms of the permissions that the user has on
@@ -417,42 +418,36 @@ def documentation_url(self):
     @property
     def owners(self):
         """Return all users who are owners of the project."""
+        session = orm_session_from_obj(self)
         owner_roles = (
-            orm.object_session(self)
-            .query(User.id)
+            session.query(User.id)
             .join(Role.user)
             .filter(Role.role_name == "Owner", Role.project == self)
             .subquery()
         )
-        return (
-            orm.object_session(self)
-            .query(User)
-            .join(owner_roles, User.id == owner_roles.c.id)
-            .all()
-        )
+        return session.query(User).join(owner_roles, User.id == owner_roles.c.id).all()
 
     @property
     def maintainers(self):
         """Return all users who are maintainers of the project."""
+        session = orm_session_from_obj(self)
         maintainer_roles = (
-            orm.object_session(self)
-            .query(User.id)
+            session.query(User.id)
             .join(Role.user)
             .filter(Role.role_name == "Maintainer", Role.project == self)
             .subquery()
         )
         return (
-            orm.object_session(self)
-            .query(User)
+            session.query(User)
             .join(maintainer_roles, User.id == maintainer_roles.c.id)
             .all()
         )
 
     @property
     def all_versions(self):
+        session = orm_session_from_obj(self)
         return (
-            orm.object_session(self)
-            .query(
+            session.query(
                 Release.version,
                 Release.created,
                 Release.is_prerelease,
@@ -466,9 +461,9 @@ def all_versions(self):
 
     @property
     def latest_version(self):
+        session = orm_session_from_obj(self)
         return (
-            orm.object_session(self)
-            .query(Release.version, Release.created, Release.is_prerelease)
+            session.query(Release.version, Release.created, Release.is_prerelease)
             .filter(Release.project == self, Release.yanked.is_(False))
             .order_by(Release.is_prerelease.nullslast(), Release._pypi_ordering.desc())
             .first()
@@ -477,7 +472,7 @@ def latest_version(self):
     @property
     def active_releases(self):
         return (
-            orm.object_session(self)
+            orm_session_from_obj(self)
             .query(Release)
             .filter(Release.project == self, Release.yanked.is_(False))
             .order_by(Release._pypi_ordering.desc())
@@ -487,7 +482,7 @@ def active_releases(self):
     @property
     def yanked_releases(self):
         return (
-            orm.object_session(self)
+            orm_session_from_obj(self)
             .query(Release)
             .filter(Release.project == self, Release.yanked.is_(True))
             .order_by(Release._pypi_ordering.desc())
@@ -747,7 +742,7 @@ def __table_args__(cls):  # noqa
     uploaded_via: Mapped[str | None]
 
     def __getitem__(self, filename: str) -> File:
-        session: orm.Session = orm.object_session(self)  # type: ignore[assignment]
+        session = orm_session_from_obj(self)
 
         try:
             return (

warehouse/utils/db/__init__.py

@@ -10,6 +10,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from warehouse.utils.db.orm import orm_session_from_obj
 from warehouse.utils.db.query_printer import print_query
 
-__all__ = ["print_query"]
+__all__ = ["orm_session_from_obj", "print_query"]

warehouse/utils/db/orm.py

@@ -0,0 +1,33 @@
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""ORM utilities."""
+
+from sqlalchemy.orm import Session, object_session
+
+
+class NoSessionError(Exception):
+    """Raised when there is no active SQLAlchemy session"""
+
+
+def orm_session_from_obj(obj) -> Session:
+    """
+    Returns the session from the ORM object.
+
+    Adds guard, but it should never happen.
+    The guard helps with type hinting, as the object_session function
+    returns Optional[Session] type.
+    """
+    session = object_session(obj)
+    if not session:
+        raise NoSessionError("Object does not have a session")
+    return session