establish sessionmaker and async_sessionmaker as generic

This is so that custom Session and AsyncSession classes
can be typed for these factories.  Added appropriate
typevars to  `__call__()`, `__enter__()` and other methods
so that a custom Session or AsyncSession subclass is carried
through.

Fixes: #7656
Change-Id: Ia2b8c1f22b4410db26005c3285f6ba3d13d7f0e0

1 files changed, 88 insertions, 0 deletions

diff --git a/test/ext/mypy/plain_files/sessionmakers.py b/test/ext/mypy/plain_files/sessionmakers.py
new file mode 100644
index 000000000..ce9b76638
--- /dev/null
+++ b/test/ext/mypy/plain_files/sessionmakers.py
@@ -0,0 +1,88 @@
+"""test #7656"""
+
+from sqlalchemy import create_engine
+from sqlalchemy import Engine
+from sqlalchemy.ext.asyncio import async_scoped_session
+from sqlalchemy.ext.asyncio import async_sessionmaker
+from sqlalchemy.ext.asyncio import AsyncEngine
+from sqlalchemy.ext.asyncio import AsyncSession
+from sqlalchemy.ext.asyncio import create_async_engine
+from sqlalchemy.orm import scoped_session
+from sqlalchemy.orm import Session
+from sqlalchemy.orm import sessionmaker
+
+
+async_engine = create_async_engine("...")
+
+
+class MyAsyncSession(AsyncSession):
+    pass
+
+
+def async_session_factory(
+    engine: AsyncEngine,
+) -> async_sessionmaker[MyAsyncSession]:
+    return async_sessionmaker(engine, class_=MyAsyncSession)
+
+
+def async_scoped_session_factory(
+    engine: AsyncEngine,
+) -> async_scoped_session[MyAsyncSession]:
+    return async_scoped_session(
+        async_sessionmaker(engine, class_=MyAsyncSession),
+        scopefunc=lambda: None,
+    )
+
+
+async def async_main() -> None:
+    fac = async_session_factory(async_engine)
+
+    async with fac() as sess:
+        # EXPECTED_TYPE: MyAsyncSession
+        reveal_type(sess)
+
+    async with fac.begin() as sess:
+        # EXPECTED_TYPE: MyAsyncSession
+        reveal_type(sess)
+
+    scoped_fac = async_scoped_session_factory(async_engine)
+
+    sess = scoped_fac()
+
+    # EXPECTED_TYPE: MyAsyncSession
+    reveal_type(sess)
+
+
+engine = create_engine("...")
+
+
+class MySession(Session):
+    pass
+
+
+def session_factory(
+    engine: Engine,
+) -> sessionmaker[MySession]:
+    return sessionmaker(engine, class_=MySession)
+
+
+def scoped_session_factory(engine: Engine) -> scoped_session[MySession]:
+    return scoped_session(sessionmaker(engine, class_=MySession))
+
+
+def main() -> None:
+    fac = session_factory(engine)
+
+    with fac() as sess:
+        # EXPECTED_TYPE: MySession
+        reveal_type(sess)
+
+    with fac.begin() as sess:
+        # EXPECTED_TYPE: MySession
+        reveal_type(sess)
+
+    scoped_fac = scoped_session_factory(engine)
+
+    sess = scoped_fac()
+    # EXPECTED_TYPE: MySession
+    reveal_type(sess)