class Closure_table_category(db.Model):
tablename = 'Closure_table_category'
id = db.Column(db.Integer, primary_key=True, autoincrement=True)
ancestor_id = db.Column(db.Integer, db.ForeignKey('
topics.id'))
descendant_id = db.Column(db.Integer, db.ForeignKey('
topics.id'))
ancestor = db.relationship('Topics', foreign_keys=[ancestor_id])
descendant = db.relationship('Topics', foreign_keys=[descendant_id])
depth = db.Column(db.Integer, nullable=False)
тут нужно колонка с primary key?