restructuring for poetry-slam

src/ttfrog/db/transaction_log.py

@@ -0,0 +1,37 @@
+import json
+import logging
+
+from ttfrog.db.manager import db
+from ttfrog.db.schema import TransactionLog
+
+
+def record(previous, new):
+    logging.debug(f"{previous = }, {new = }")
+    diff = list((set(previous.items()) ^ set(dict(new).items())))
+    if not diff:
+        return
+
+    rec = TransactionLog(
+        source_table_name=new.__tablename__,
+        primary_key=new.id,
+        diff=json.dumps(diff),
+    )
+    with db.transaction():
+        db.add(rec)
+        logging.debug(f"Saved restore point: {dict(rec)}")
+        return rec
+
+
+def restore(rec, log_id=None):
+    if log_id:
+        log = db.query(TransactionLog).filter_by(id=log_id).one()
+    else:
+        log = db.query(TransactionLog).filter_by(source_table_name=rec.__tablename__, primary_key=rec.id).one()
+    logging.debug(f"Located restore point {log = }")
+    diff = json.loads(log.diff)
+    updates = dict(diff[::2])
+    if not updates:
+        return
+    logging.debug(f"{updates = }")
+    with db.transaction():
+        db.query(db.tables[log.source_table_name]).update(updates)