我有一个看起来像这样的模型:
class Foo(db.Model):
id = db.Column(db.Integer, primary_key=True)
# omitted lengthy codes...
spam = db.relationship('Spam')
spam_id = db.Column(db.Integer, db.ForeignKey('spams.id'))
bar = db.relationship('Bar')
bar_id = db.Column(db.Integer, db.ForeignKey('bars.id'))
created = db.Column(db.DateTime, server_default=db.func.now())
Flask-SQLAlchemy是否有任何选项可以添加spam_id
和bar_id
在插入/更新期间不能同时为None
的行为?但是,如果这些列中至少有一列具有值,则会接受。
from sqlalchemy import CheckConstraint
class Foo(db.Model):
id = db.Column(db.Integer, primary_key=True)
# omitted lengthy codes...
spam = db.relationship('Spam')
spam_id = db.Column(db.Integer, db.ForeignKey('spams.id'))
bar = db.relationship('Bar')
bar_id = db.Column(db.Integer, db.ForeignKey('bars.id'))
created = db.Column(db.DateTime, server_default=db.func.now())
__table_args__ = (
CheckConstraint('NOT(spam_id IS NULL AND bar_id IS NULL)', name='both_null'),
)
尝试添加带有spam_id的新Foo实例和None?好的,你可以
foo=Foo(spam_id=None, bar_id=1)
sqlalchemy_session.add(foo)
sqlalchemy_session.commit()
尝试添加Foo,其中spam_id和bar_id都是无?不,先生!
foo=Foo(spam_id=None, bar_id=None)
sqlalchemy_session.add(foo)
sqlalchemy_session.commit() # Raises Exception
引发的异常来自您的DBMS,例如使用PostgresQL和psycopg2驱动程序它是psycopg2.IntegrityError