refac: replace timestamp field

backend/apps/web/internal/migrations/005_add_updated_at.py

@@ -0,0 +1,77 @@
+"""Peewee migrations -- 002_add_local_sharing.py.
+
+Some examples (model - class or model name)::
+
+    > Model = migrator.orm['table_name']            # Return model in current state by name
+    > Model = migrator.ModelClass                   # Return model in current state by name
+
+    > migrator.sql(sql)                             # Run custom SQL
+    > migrator.run(func, *args, **kwargs)           # Run python function with the given args
+    > migrator.create_model(Model)                  # Create a model (could be used as decorator)
+    > migrator.remove_model(model, cascade=True)    # Remove a model
+    > migrator.add_fields(model, **fields)          # Add fields to a model
+    > migrator.change_fields(model, **fields)       # Change fields
+    > migrator.remove_fields(model, *field_names, cascade=True)
+    > migrator.rename_field(model, old_field_name, new_field_name)
+    > migrator.rename_table(model, new_table_name)
+    > migrator.add_index(model, *col_names, unique=False)
+    > migrator.add_not_null(model, *field_names)
+    > migrator.add_default(model, field_name, default)
+    > migrator.add_constraint(model, name, sql)
+    > migrator.drop_index(model, *col_names)
+    > migrator.drop_not_null(model, *field_names)
+    > migrator.drop_constraints(model, *constraints)
+
+"""
+
+from contextlib import suppress
+
+import peewee as pw
+from peewee_migrate import Migrator
+
+
+with suppress(ImportError):
+    import playhouse.postgres_ext as pw_pext
+
+
+def migrate(migrator: Migrator, database: pw.Database, *, fake=False):
+    """Write your migrations here."""
+
+    # Adding fields created_at and updated_at to the 'chat' table
+    migrator.add_fields(
+        "chat",
+        created_at=pw.DateTimeField(null=True),  # Allow null for transition
+        updated_at=pw.DateTimeField(null=True),  # Allow null for transition
+    )
+
+    # Populate the new fields from an existing 'timestamp' field
+    migrator.sql(
+        "UPDATE chat SET created_at = timestamp, updated_at = timestamp WHERE timestamp IS NOT NULL"
+    )
+
+    # Now that the data has been copied, remove the original 'timestamp' field
+    migrator.remove_fields("chat", "timestamp")
+
+    # Update the fields to be not null now that they are populated
+    migrator.change_fields(
+        "chat",
+        created_at=pw.DateTimeField(null=False),
+        updated_at=pw.DateTimeField(null=False),
+    )
+
+
+def rollback(migrator: Migrator, database: pw.Database, *, fake=False):
+    """Write your rollback migrations here."""
+
+    # Recreate the timestamp field initially allowing null values for safe transition
+    migrator.add_fields("chat", timestamp=pw.DateTimeField(null=True))
+
+    # Copy the earliest created_at date back into the new timestamp field
+    # This assumes created_at was originally a copy of timestamp
+    migrator.sql("UPDATE chat SET timestamp = created_at")
+
+    # Remove the created_at and updated_at fields
+    migrator.remove_fields("chat", "created_at", "updated_at")
+
+    # Finally, alter the timestamp field to not allow nulls if that was the original setting
+    migrator.change_fields("chat", timestamp=pw.DateTimeField(null=False))