Creating partial unique index with sqlalchemy on Postgres

Question

SQLAlchemy supports creating partial indexes in postgresql.

Is it possible to create a partial unique index through SQLAlchemy?

Imagine a table/model as so:<

Answer 1

In case someone stops by looking to set up a partial unique constraint with a column that can optionally be NULL, here's how:

__table_args__ = (
    db.Index(
        'uk_providers_name_category',
        'name', 'category',
        unique=True,
        postgresql_where=(user_id.is_(None))),
    db.Index(
        'uk_providers_name_category_user_id',
        'name', 'category', 'user_id',
        unique=True,
        postgresql_where=(user_id.isnot(None))),
)

where user_id is a column that can be NULL and I want a unique constraint enforced across all three columns (name, category, user_id) with NULL just being one of the allowed values for user_id.