Fetch table values using alembic and update to another table.

Question

I have oauth secret and oauth key in client table. Now I moving them to oauth credentials table which will be created during

Answer 1

You can create a DBSession with sqlalchemy engine bind, then you can avoid use SQL query.

from myapp.models import Client, ClientCredential
from alembic import op, context
import sqlalchemy as sa


def upgrade():
    ### commands auto generated by Alembic - please adjust! ###
    url = context.config.get_main_option("sqlalchemy.url")
    engine = sa.create_engine(url)
    DBSession.configure(bind=engine)

    op.create_table(
        'client_credential',
        sa.Column('id', sa.Integer(), nullable=False),
        sa.Column('created_at', sa.DateTime(), nullable=False),
        sa.Column('updated_at', sa.DateTime(), nullable=False),
        sa.Column('client_id', sa.Integer(), nullable=False),
        sa.Column('key', sa.String(length=22), nullable=False),
        sa.Column('secret', sa.String(length=44), nullable=False),
        sa.Column('is_active', sa.Boolean(), nullable=False),
        sa.ForeignKeyConstraint(['client_id'], ['client.id'], ),
        sa.PrimaryKeyConstraint('id'),
        sa.UniqueConstraint('key'))
    # Here I need to copy data from table A to newly created Table.
    # Now Client table will not have secret and key attributes
    clients = [
        {'secret': client.secret,
         'key': client.key,
         'is_active': True,
         'client_id': client.id,
         'created_at': sa.func.now(),
         'updated_at': sa.func.now()}
        for client in Client.query.all()]
    op.bulk_insert(ClientCredential, clients)
    #Also replaced above two lines with
    #connection = op.get_bind()
    #print connection.execute(Client, Client.query.all())
    op.drop_column(u'client', u'secret')
    op.drop_column(u'client', u'key')

Answer 2

Maybe try adding a column_reflect listener? E.g.:

def listen_for_reflect(inspector, table, column_info):
    "correct an ENUM type"
    if column_info['name'] == 'my_enum':
        column_info['type'] = Enum('a', 'b', 'c')

with self.op.batch_alter_table(
    "bar",
    reflect_kwargs=dict(
        listeners=[
            ('column_reflect', listen_for_reflect)
        ]
    )
) as batch_op:
    batch_op.alter_column(
        'flag', new_column_name='bflag', existing_type=Boolean)

More info: https://alembic.zzzcomputing.com/en/latest/batch.html#controlling-table-reflection

Answer 3

Finally I solved the problem. Created raw sql to fetch the values and used bulk_insert.

def upgrade():
    ### commands auto generated by Alembic - please adjust! ###
    op.create_table('client_credential',
    sa.Column('id', sa.Integer(), nullable=False),
    sa.Column('created_at', sa.DateTime(), nullable=False),
    sa.Column('updated_at', sa.DateTime(), nullable=False),
    sa.Column('client_id', sa.Integer(), nullable=False),
    sa.Column('key', sa.String(length=22), nullable=False),
    sa.Column('secret', sa.String(length=44), nullable=False),
    sa.Column('is_active', sa.Boolean(), nullable=False),
    sa.ForeignKeyConstraint(['client_id'], ['client.id'], ),
    sa.PrimaryKeyConstraint('id'),
    sa.UniqueConstraint('key')
    )
    #http://stackoverflow.com/questions/15725859/sqlalchemy-alembic-bulk-insert-fails-str-object-has-no-attribute-autoincre
    client_credential = sa.sql.table('client_credential',
        sa.Column('client_id', sa.Integer, nullable=False),
        sa.Column('is_active', sa.Boolean, nullable=False, default=True),
        sa.Column('key', sa.String(22), nullable=False, default=True),
        sa.Column('secret', sa.String(22), nullable=False, default=True),
        sa.Column('created_at', sa.DateTime, nullable=False, default=sa.func.now()),
        sa.Column('updated_at', sa.DateTime, nullable=False, default=sa.func.now()),
    )
    conn = op.get_bind()
    res = conn.execute("select secret, key, id from client")
    results = res.fetchall()
    clients = [{'secret': r[0], 'key': r[1], 'is_active':True, 'client_id': r[2], 'created_at': datetime.datetime.now(), 'updated_at': datetime.datetime.now()} for r in results]
    op.bulk_insert(client_credential, clients)
    op.drop_column(u'client', u'secret')
    op.drop_column(u'client', u'key')
    ### end Alembic commands ###