Flask-migrate: I'm trying to remove a unique=True from one of my columns.

[rlam3]

I'm trying to remove a unique=True from one of my columns. But I don't see any documentation on how to set unique=False in the docs.

I've come across some alembic docs but I'm still not sure if this is the proper way to do it.... And how am I supposed to find my constraint name? I assume that these unique constraint names were automatically assigned.

I followed the following source to drop the constraint but it seems that

op.drop_constraint("title",
    "book",
    "unique")

is not working ..

error message:

sqlalchemy.exc.ProgrammingError: (psycopg2.ProgrammingError) constraint "title" of relation "book" does not exist.

Source:
http://skien.cc/blog/2014/01/31/adding-unique-contraints-after-the-fact-in-sqlalchemy/

[miguelgrinberg]

Did you look in the migration where this constraint was added? That should show you the name of your constraint, I think.

[rlam3]

@miguelgrinberg

This is what I see...

...version.py
op.create_index(op.f('ix_book_title'), 'book', ['title'], unique=True)

I replaced the "title" with "ix_book_title" but it is saying that it doesn't see it

sqlalchemy.exc.ProgrammingError: (psycopg2.ProgrammingError) constraint "ix_book_title" of relation "book" does not exist
 [SQL: 'ALTER TABLE book DROP CONSTRAINT ix_book_title']

[miguelgrinberg]

Did you try drop_index instead of drop_constraint?

[rlam3]

I think you need to drop the index and the constraint...

Is it possible to detect this for future changes from unique=True to unique=False?

[tedivm]

I know where like three years later but I'm hitting this issue now and am curious how it got solved.

[tedivm]

If anyone else finds this it seems like the constraint is named TABLE_COLUMN_key.

Removing the unique constraint from the column name on the table experiments would look like this-

def upgrade():
    op.drop_constraint('experiments_name_key', 'experiments')

def downgrade():
    op.create_unique_constraint('experiments_name_key', 'experiments', ['name'])

[Aekanshu]

i am also getting the same problem does anyone solved it yet ?