Data transfer script (#114)

Transfers data betwenn two sql instances.
Limited in data volume. Should be good enough for now.

---------

Co-authored-by: Tim <tim.ronneburg@outlook.de>

README.md

@@ -14,7 +14,7 @@ See the [CONTRIBUTING.md](CONTRIBUTING.md) about how code should be formatted an
 
 ## DB Connection settings
 
-To connect to the SQL db see [sql/connector.py](./src/aki_prj23_transparenzregister/utils/postgres/connector.py)
+To connect to the SQL db see [sql/connector.py](./src/aki_prj23_transparenzregister/utils/sql/connector.py)
 To connect to the Mongo db see [connect]
 
 Create a `secrets.json` in the root of this repo with the following structure (values to be replaces by desired config):
@@ -38,8 +38,10 @@ Create a `secrets.json` in the root of this repo with the following structure (v
 }
 ```
 
-Alternatively, the secrets can be provided as environment variables. One option to do so is to add a `.env` file with the following layout:
-```ini
+Alternatively, the secrets can be provided as environment variables. One option to do so is to add a `.env` file with
+the following layout:
+
+```
 PYTHON_POSTGRES_USERNAME=postgres
 PYTHON_POSTGRES_PASSWORD=postgres
 PYTHON_POSTGRES_HOST=localhost

src/aki_prj23_transparenzregister/utils/sql/connector.py

@@ -1,11 +1,13 @@
 """Module containing connection utils for PostgreSQL DB."""
 import re
 
+import pandas as pd
 import sqlalchemy as sa
 from loguru import logger
 from sqlalchemy.engine import URL, Engine
 from sqlalchemy.orm import Session, declarative_base, sessionmaker
 from sqlalchemy.pool import SingletonThreadPool
+from tqdm import tqdm
 
 from aki_prj23_transparenzregister.config.config_providers import (
     ConfigProvider,
@@ -83,11 +85,31 @@ def init_db(db: Session) -> None:
 
 def reset_all_tables(db: Session) -> None:
     """Drops all SQL tables and recreates them."""
-    logger.info("Resetting all PostgreSQL tables.")
+    logger.info("Resetting all SQL tables.")
     Base.metadata.drop_all(db.bind)
     init_db(db)
 
 
+@logger.catch(reraise=True)
+def transfer_db(*, source: Session, destination: Session) -> None:
+    """Transfers the data from on db to another db.
+
+    Args:
+        source: A session to a source db data should be copied from.
+        destination: A session to a db where the data should be copied to.
+    """
+    reset_all_tables(destination)
+    init_db(destination)
+    sbind = source.bind
+    dbind = destination.bind
+    assert isinstance(sbind, Engine)  # noqa: S101
+    assert isinstance(dbind, Engine)  # noqa: S101
+    for table in tqdm(Base.metadata.sorted_tables):
+        pd.read_sql_table(str(table), sbind).to_sql(
+            str(table), dbind, if_exists="append", index=False
+        )
+
+
 if __name__ == "__main__":
     """Main flow creating tables"""
     init_db(get_session(JsonFileConfigProvider("./secrets.json")))

tests/utils/data_extraction/__init__.py

@@ -1 +0,0 @@
-"""Tests for data_extraction."""

tests/utils/sql/connector_test.py

@@ -4,15 +4,19 @@ from collections.abc import Generator
 from typing import Any
 from unittest.mock import Mock, patch
 
+import pandas as pd
 import pytest
 from sqlalchemy.engine import Engine
+from sqlalchemy.orm import Session
 
 from aki_prj23_transparenzregister.config.config_providers import JsonFileConfigProvider
 from aki_prj23_transparenzregister.config.config_template import PostgreConnectionString
 from aki_prj23_transparenzregister.utils.sql.connector import (
+    Base,
     get_pg_engine,
     get_session,
     init_db,
+    transfer_db,
 )
 
 
@@ -27,6 +31,36 @@ def test_get_engine_pg() -> None:
         assert get_pg_engine(conn_args) == result
 
 
+@pytest.fixture()
+def destination_db() -> Generator[Session, None, None]:
+    """Generates a db Session to a sqlite db to copy data to."""
+    if os.path.exists("secondary.db"):
+        os.remove("secondary.db")
+    db = get_session("sqlite:///secondary.db")
+    init_db(db)
+    yield db
+    db.close()
+    bind = db.bind
+    assert isinstance(bind, Engine)
+    bind.dispose()
+    os.remove("secondary.db")
+
+
+def test_transfer_db(full_db: Session, destination_db: Session) -> None:
+    """Tests if the data transfer between two sql tables works."""
+    transfer_db(source=full_db, destination=destination_db)
+    sbind = full_db.bind
+    dbind = destination_db.bind
+    assert isinstance(sbind, Engine)
+    assert isinstance(dbind, Engine)
+
+    for table in Base.metadata.sorted_tables:
+        pd.testing.assert_frame_equal(
+            pd.read_sql_table(str(table), dbind),
+            pd.read_sql_table(str(table), sbind),
+        )
+
+
 @pytest.fixture()
 def delete_sqlite_table() -> Generator[str, None, None]:
     """Cleans a path before and deletes the table after a test.