Place editing

mo/db.py

@@ -5,9 +5,10 @@ from enum import Enum as PythonEnum, auto
 from sqlalchemy import \
     Boolean, Column, DateTime, Enum, ForeignKey, Integer, String, Text, UniqueConstraint, \
     text, \
-    create_engine
+    create_engine, inspect
 from sqlalchemy.engine import Engine
-from sqlalchemy.orm import relationship, sessionmaker, Session
+from sqlalchemy.orm import relationship, sessionmaker, Session, class_mapper
+from sqlalchemy.orm.attributes import get_history
 from sqlalchemy.dialects.postgresql import JSONB
 from sqlalchemy.ext.declarative import declarative_base
 from typing import Optional, List
@@ -289,3 +290,30 @@ def get_place_parents(place: Place) -> List[Place]:
     recq = topq.union(botq)
 
     return sess.query(recq).all()
+
+
+def get_object_changes(obj):
+    """ Given a model instance, returns dict of pending
+    changes waiting for database flush/commit.
+
+    e.g. {
+        'some_field': {
+            'before': *SOME-VALUE*,
+            'after': *SOME-VALUE*
+        },
+        ...
+    }
+
+    Source: https://stackoverflow.com/questions/15952733/sqlalchemy-logging-of-changes-with-date-and-user
+    """
+    inspection = inspect(obj)
+    changes = {}
+    for attr in class_mapper(obj.__class__).column_attrs:
+        if getattr(inspection.attrs, attr.key).history.has_changes():
+            if get_history(obj, attr.key)[2]:
+                before = get_history(obj, attr.key)[2].pop()
+                after = getattr(obj, attr.key)
+                if before != after:
+                    if before or after:
+                        changes[attr.key] = {'before': before, 'after': after}
+    return changes