Hi Mike, I've just checked my code and I noticed that I already use existing_type (not sure what was wrong with the documentation in that aspect).
Can you elaborate a bit on specifying custom rules as you mentioned? I tried issuing a drop_constraint before calling the alter_column but that doesn't stop alter_column from trying to remove the check constraint by itself, leading to the same exception. On the other hand, I didn't see any parameter in the alter_column method that accepts a constraint name Thanks, Ofir On Thursday, December 10, 2015 at 3:39:42 PM UTC+2, Ofir Herzas wrote: > > I'm trying to run an alter_column operation from a Boolean type column to > SmallInteger on Oracle. > > According to the documentation: "...Type changes which are against the > SQLAlchemy “schema” types Boolean > <http://www.sqlalchemy.org/docs/core/type_basics.html#sqlalchemy.types.Boolean> > and Enum > <http://www.sqlalchemy.org/docs/core/type_basics.html#sqlalchemy.types.Enum> > may > also add or drop constraints which accompany those types on backends that > don’t support them natively. The existing_server_default argument is used > in this case as well to remove a previous constraint...." > > Does this mean that the alter column should work out-of-the-box or do I > have to remove the constraint myself because I'm getting the following > error on alembic 0.8.3 (sqlalchemy 1.0.9): > > sqlalchemy.exc.CompileError: Can't emit DROP CONSTRAINT for constraint > CheckConstraint(<sqlalchemy.sql.elements.BinaryExpression object at > 0x28a9b10>, name='_unnamed_', table=Table('t_message', > MetaData(bind=None), Column('is_bulletin', Boolean(), table=<t_message>), > schema=None), > _create_rule=<sqlalchemy.util.langhelpers.portable_instancemethod object at > 0x289ac68>, _type_bound=True); it has no name > > > And on a previous version (alembic 0.6.5, sqlalchemy 0.9.7) I got the > following error: > > sqlalchemy.exc.DatabaseError: (DatabaseError) ORA-02443: Cannot drop > constraint - nonexistent constraint > 'ALTER TABLE t_message DROP CONSTRAINT None' {} > > > Your help will be appreciated... > -- You received this message because you are subscribed to the Google Groups "sqlalchemy-alembic" group. To unsubscribe from this group and stop receiving emails from it, send an email to sqlalchemy-alembic+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
