batch_op.alter_column fails for server_default=None

[sqlalchemy-bot]

Migrated issue, originally created by Martin Domke (@mdomke)

It is currently not possible to delete an existing server default when using batch_alter_table() by setting the server_default keyword-parameter to None. The migration will fail with an

sqlalchemy.exc.ArgumentError: Argument 'arg' is expected to be one of type '<type 'basestring'>' or '<class 'sqlalchemy.sql.elements.ClauseElement'>' or '<class 'sqlalchemy.sql.elements.TextClause'>', got '<type 'NoneType'>'

I suppose this has been introduced in issue #338. Following the example from that issue, the following doesn't work:

Revision 1:

def upgrade():
    op.create_table(
      'test',
      sa.Column('integer', sa.Integer, nullable=False, primary_key=True),
      sa.Column('string', sa.Text, nullable=False, server_default='default'),
    )

Revision 2:

def upgrade():
    with op.batch_alter_table('test') as batch_op:
        batch_op.alter_column('string', server_default=None)

[sqlalchemy-bot]

Michael Bayer (@zzzeek) wrote:

• changelog for batch_op.alter_column fails for server_default=None #361, fixes batch_op.alter_column fails for server_default=None #361
• rename test

→ 11ad2a8

[sqlalchemy-bot]

Changes by Michael Bayer (@zzzeek):

• changed status to closed

[sqlalchemy-bot]

Michael Bayer (@zzzeek) wrote:

thanks!