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"""Add description field to ``connection`` table

Revision ID: 61ec73d9401f
Revises: 2c6edca13270
Create Date: 2020-09-10 14:56:30.279248

"""

import sqlalchemy as sa
from alembic import op

# revision identifiers, used by Alembic.
revision = '61ec73d9401f'
down_revision = '2c6edca13270'
branch_labels = None
depends_on = None
airflow_version = '2.0.0'


def upgrade():
    """Apply Add description field to ``connection`` table"""
    conn = op.get_bind()

    with op.batch_alter_table('connection') as batch_op:
        if conn.dialect.name == "mysql":
            # Handles case where on mysql with utf8mb4 this would exceed the size of row
            # We have to set text type in this migration even if originally it was string
            # This is permanently fixed in the follow-up migration 64a7d6477aae
            batch_op.add_column(sa.Column('description', sa.Text(length=5000), nullable=True))
        else:
            batch_op.add_column(sa.Column('description', sa.String(length=5000), nullable=True))


def downgrade():
    """Unapply Add description field to ``connection`` table"""
    with op.batch_alter_table('connection', schema=None) as batch_op:
        batch_op.drop_column('description')
