feat: add support for using postgres for the backend DB

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

@@ -37,6 +37,13 @@ with suppress(ImportError):
 def migrate(migrator: Migrator, database: pw.Database, *, fake=False):
     """Write your migrations here."""
 
+    if isinstance(database, pw.SqliteDatabase):
+        migrate_sqlite(migrator, database, fake=fake)
+    else:
+        migrate_external(migrator, database, fake=fake)
+
+
+def migrate_sqlite(migrator: Migrator, database: pw.Database, *, fake=False):
     # Adding fields created_at and updated_at to the 'chat' table
     migrator.add_fields(
         "chat",
@@ -60,9 +67,40 @@ def migrate(migrator: Migrator, database: pw.Database, *, fake=False):
     )
 
 
+def migrate_external(migrator: Migrator, database: pw.Database, *, fake=False):
+    # Adding fields created_at and updated_at to the 'chat' table
+    migrator.add_fields(
+        "chat",
+        created_at=pw.BigIntegerField(null=True),  # Allow null for transition
+        updated_at=pw.BigIntegerField(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.BigIntegerField(null=False),
+        updated_at=pw.BigIntegerField(null=False),
+    )
+
+
 def rollback(migrator: Migrator, database: pw.Database, *, fake=False):
     """Write your rollback migrations here."""
 
+    if isinstance(database, pw.SqliteDatabase):
+        rollback_sqlite(migrator, database, fake=fake)
+    else:
+        rollback_external(migrator, database, fake=fake)
+
+
+def rollback_sqlite(migrator: Migrator, database: pw.Database, *, fake=False):
     # Recreate the timestamp field initially allowing null values for safe transition
     migrator.add_fields("chat", timestamp=pw.DateTimeField(null=True))
 
@@ -75,3 +113,18 @@ def rollback(migrator: Migrator, database: pw.Database, *, fake=False):
 
     # Finally, alter the timestamp field to not allow nulls if that was the original setting
     migrator.change_fields("chat", timestamp=pw.DateTimeField(null=False))
+
+
+def rollback_external(migrator: Migrator, database: pw.Database, *, fake=False):
+    # Recreate the timestamp field initially allowing null values for safe transition
+    migrator.add_fields("chat", timestamp=pw.BigIntegerField(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.BigIntegerField(null=False))