superset/migrations/versions/07071313dd52_change_fetch_values_predicate_to_text.py

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"""change_fetch_values_predicate_to_text

Revision ID: 07071313dd52
Revises: 6d20ba9ecb33
Create Date: 2021-08-09 17:32:56.204184

"""

# revision identifiers, used by Alembic.
revision = "07071313dd52"
down_revision = "6d20ba9ecb33"

import logging

import sqlalchemy as sa
from alembic import op
from sqlalchemy import and_, func, or_
from sqlalchemy.dialects import postgresql
from sqlalchemy.sql.schema import Table

from superset import db
from superset.connectors.sqla.models import SqlaTable


def upgrade():
    with op.batch_alter_table("tables") as batch_op:
        batch_op.alter_column(
            "fetch_values_predicate",
            existing_type=sa.String(length=1000),
            type_=sa.Text(),
            existing_nullable=True,
        )


def remove_value_if_too_long():
    bind = op.get_bind()
    session = db.Session(bind=bind)

    # it will be easier for users to notice that their field has been deleted rather than truncated
    # so just remove it if it won't fit back into the 1000 string length column
    try:
        rows = (
            session.query(SqlaTable)
            .filter(func.length(SqlaTable.fetch_values_predicate) > 1000)
            .all()
        )

        for row in rows:
            row.fetch_values_predicate = None

        logging.info("%d values deleted", len(rows))

        session.commit()
        session.close()
    except Exception as ex:
        logging.warning(ex)


def downgrade():
    remove_value_if_too_long()

    with op.batch_alter_table("tables") as batch_op:
        batch_op.alter_column(
            "fetch_values_predicate",
            existing_type=sa.Text(),
            type_=sa.String(length=1000),
            existing_nullable=True,
        )