Why Uniqueconstraint Doesn't Work In Flask_sqlalchemy

I want an alternative of Django's unique_together in flask, seems UniqueConstraint is what I'm looking for, but doesn't work for me. here is the example: import os from flask impor

Solution 1:

An instance of UniqueConstraint is iterable and in this case seems to stop iteration immediately, so

tuple(db.UniqueConstraint('name', 'address'))

results in an empty tuple, when you wanted a tuple that contains 1 item, the constraint instance. Use

__table_args__ = (db.UniqueConstraint('name', 'address'), )

or any other variation instead. As to why the latter form does not work, you must apply table-level constraint objects using __table_args__ in declarative.

Solution 2:

Passing variable names ( instead of strings ) worked for me.

classUser(db.Model):
    __tablename__ = 'users'id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(64), nullable=False)
    address = db.Column(db.String(64), nullable=False)
    db.UniqueConstraint(name, address)