community[patch]: restore compatibility with SQLAlchemy 1.x (#22546)

- **Description:** Restores compatibility with SQLAlchemy 1.4.x that was
broken since #18992 and adds a test run for this version on CI (only for
Python 3.11)
- **Issue:** fixes #19681
- **Dependencies:** None
- **Twitter handle:** `@krassowski_m`

---------

Co-authored-by: Erick Friis <erick@langchain.dev>

libs/community/tests/unit_tests/chat_message_histories/test_sql.py

@@ -4,7 +4,17 @@ from typing import Any, AsyncGenerator, Generator, List, Tuple
 import pytest
 from langchain_core.messages import AIMessage, BaseMessage, HumanMessage
 from sqlalchemy import Column, Integer, Text
-from sqlalchemy.orm import DeclarativeBase
+
+try:
+    from sqlalchemy.orm import DeclarativeBase
+
+    class Base(DeclarativeBase):
+        pass
+except ImportError:
+    # for sqlalchemy < 2
+    from sqlalchemy.ext.declarative import declarative_base
+
+    Base = declarative_base()  # type:ignore
 
 from langchain_community.chat_message_histories import SQLChatMessageHistory
 from langchain_community.chat_message_histories.sql import DefaultMessageConverter
@@ -198,9 +208,6 @@ async def test_async_clear_messages(
 
 
 def test_model_no_session_id_field_error(con_str: str) -> None:
-    class Base(DeclarativeBase):
-        pass
-
     class Model(Base):
         __tablename__ = "test_table"
         id = Column(Integer, primary_key=True)

libs/community/tests/unit_tests/test_sql_database.py

@@ -1,21 +1,25 @@
 # flake8: noqa: E501
 """Test SQL database wrapper."""
+
 import pytest
 import sqlalchemy as sa
+from packaging import version
 from sqlalchemy import (
     Column,
     Integer,
     MetaData,
-    Result,
     String,
     Table,
     Text,
     insert,
     select,
 )
+from sqlalchemy.engine import Engine, Result
 
 from langchain_community.utilities.sql_database import SQLDatabase, truncate_word
 
+is_sqlalchemy_v1 = version.parse(sa.__version__).major == 1
+
 metadata_obj = MetaData()
 
 user = Table(
@@ -35,18 +39,18 @@ company = Table(
 
 
 @pytest.fixture
-def engine() -> sa.Engine:
+def engine() -> Engine:
     return sa.create_engine("sqlite:///:memory:")
 
 
 @pytest.fixture
-def db(engine: sa.Engine) -> SQLDatabase:
+def db(engine: Engine) -> SQLDatabase:
     metadata_obj.create_all(engine)
     return SQLDatabase(engine)
 
 
 @pytest.fixture
-def db_lazy_reflection(engine: sa.Engine) -> SQLDatabase:
+def db_lazy_reflection(engine: Engine) -> SQLDatabase:
     metadata_obj.create_all(engine)
     return SQLDatabase(engine, lazy_table_reflection=True)
 
@@ -230,6 +234,7 @@ def test_sql_database_run_update(db: SQLDatabase) -> None:
     assert output == expected_output
 
 
+@pytest.mark.skipif(is_sqlalchemy_v1, reason="Requires SQLAlchemy 2 or newer")
 def test_sql_database_schema_translate_map() -> None:
     """Verify using statement-specific execution options."""