refac: file table migration

backend/open_webui/migrations/versions/c29facfe716b_update_file_table_path.py

@@ -0,0 +1,79 @@
+"""Update file table path
+
+Revision ID: c29facfe716b
+Revises: c69f45358db4
+Create Date: 2024-10-20 17:02:35.241684
+
+"""
+
+from alembic import op
+import sqlalchemy as sa
+import json
+from sqlalchemy.sql import table, column
+from sqlalchemy import String, Text, JSON, and_
+
+
+revision = "c29facfe716b"
+down_revision = "c69f45358db4"
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    # 1. Add the `path` column to the "file" table.
+    op.add_column("file", sa.Column("path", sa.Text(), nullable=True))
+
+    # 2. Convert the `meta` column from Text/JSONField to `JSON()`
+    # Use Alembic's default batch_op for dialect compatibility.
+    with op.batch_alter_table("file", schema=None) as batch_op:
+        batch_op.alter_column(
+            "meta",
+            type_=sa.JSON(),
+            existing_type=sa.Text(),
+            existing_nullable=True,
+            nullable=True,
+            postgresql_using="meta::json",
+        )
+
+    # 3. Migrate legacy data from `meta` JSONField
+    # Fetch and process `meta` data from the table, add values to the new `path` column as necessary.
+    # We will use SQLAlchemy core bindings to ensure safety across different databases.
+
+    file_table = table(
+        "file", column("id", String), column("meta", JSON), column("path", Text)
+    )
+
+    # Create connection to the database
+    connection = op.get_bind()
+
+    # Get the rows where `meta` has a path and `path` column is null (new column)
+    # Loop through each row in the result set to update the path
+    results = connection.execute(
+        sa.select(file_table.c.id, file_table.c.meta).where(
+            and_(file_table.c.path.is_(None), file_table.c.meta.isnot(None))
+        )
+    ).fetchall()
+
+    # Iterate over each row to extract and update the `path` from `meta` column
+    for row in results:
+        if "path" in row.meta:
+            # Extract the `path` field from the `meta` JSON
+            path = row.meta.get("path")
+
+            # Update the `file` table with the new `path` value
+            connection.execute(
+                file_table.update()
+                .where(file_table.c.id == row.id)
+                .values({"path": path})
+            )
+
+
+def downgrade():
+    # 1. Remove the `path` column
+    op.drop_column("file", "path")
+
+    # 2. Revert the `meta` column back to Text/JSONField
+    with op.batch_alter_table("file", schema=None) as batch_op:
+        batch_op.alter_column(
+            "meta", type_=sa.Text(), existing_type=sa.JSON(), existing_nullable=True
+        )