sensors is separate API with td

server/migrate_legacy_db.py

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+"""Copy data from a legacy combined data.db into the split databases.
+
+The legacy database contained users, sensors and readouts in one file. Run the
+new migrations first, then import the old rows:
+
+    alembic upgrade head
+    alembic -c alembic_users.ini upgrade head
+    python migrate_legacy_db.py
+
+The legacy file is only read; nothing is deleted from it.
+"""
+
+import argparse
+from pathlib import Path
+
+from sqlalchemy import MetaData, Table, create_engine, inspect, select
+from sqlalchemy.dialects.sqlite import insert
+
+from models import Sensor, SensorReadout
+from user_models import User
+
+
+def _sqlite_engine(path: Path):
+    if not path.exists():
+        raise SystemExit(f"database not found: {path}")
+    return create_engine(f"sqlite:///{path}")
+
+
+def _copy_table(source, destination, table) -> int:
+    if table.name not in inspect(source).get_table_names():
+        return 0
+
+    source_table = Table(table.name, MetaData(), autoload_with=source)
+    with source.connect() as conn:
+        rows = [dict(row._mapping) for row in conn.execute(select(source_table))]
+    if not rows:
+        return 0
+
+    with destination.begin() as conn:
+        conn.execute(insert(table).on_conflict_do_nothing(), rows)
+    return len(rows)
+
+
+def main() -> None:
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument("--legacy", default="data.db", type=Path)
+    parser.add_argument("--sensors", default="sensors.db", type=Path)
+    parser.add_argument("--main-app", default="main_app.db", type=Path)
+    args = parser.parse_args()
+
+    legacy = _sqlite_engine(args.legacy)
+    sensors = _sqlite_engine(args.sensors)
+    main_app = _sqlite_engine(args.main_app)
+
+    if not inspect(sensors).has_table(Sensor.__tablename__):
+        raise SystemExit(f"{args.sensors} has no schema; run alembic upgrade head first")
+    if not inspect(main_app).has_table(User.__tablename__):
+        raise SystemExit(
+            f"{args.main_app} has no schema; run alembic -c alembic_users.ini upgrade head first"
+        )
+
+    sensor_count = _copy_table(legacy, sensors, Sensor.__table__)
+    readout_count = _copy_table(legacy, sensors, SensorReadout.__table__)
+    user_count = _copy_table(legacy, main_app, User.__table__)
+
+    print(
+        f"Copied {sensor_count} sensors, {readout_count} readouts and "
+        f"{user_count} users. The legacy database was not modified."
+    )
+
+
+if __name__ == "__main__":
+    main()