[SOLVED] Is it possible to drop a unique constraint from a column?

Is it possible to drop a unique constraint from a column?

I've tried simply removing the unique=True constraint and running

flask db migrate
flask db upgrade

in the command line but when I run my flask app I'm still getting a (sqlite3.IntegrityError) UNIQUE constraint failed error.

Is there a simple way to do this with flask-migrate or should I switch to alembic (which I know flask-migrate is just wrapped around)? I would prefer not to drop the entire table. Thanks for any help!

Solution

Flask-Migrate, or rather Alembic, will not autodetect anonymous constraints. But you can create a manual Alembic migration file to drop the constraint.

Create an empty migration file:

flask db revision -m 'Drop unique constraint'

Edit the file to drop the constraint:

def upgrade():
    op.drop_constraint("name_of_constraint", "table_name")

def downgrade():
    op.create_index(...)

I suggest you copy the create_index from the migration file that created the constraint in the first place, if possible.

Then you can upgrade your database normally:

flask db upgrade