2
我是sqlalchemy的新手。我想創建一個有兩個外鍵用於不同表的類。爲什麼我得到下一個錯誤？sqlalchemy，違反外鍵約束
sqlalchemy.exc.IntegrityError: (IntegrityError) insert or update on table "event" violates foreign key constraint "event_user_fkey"
DETAIL: Key (user)=(U) is not present in table "user".
'INSERT INTO event (id, "user", item) VALUES (%(id)s, %(user)s, %(item)s)' {'item': 'I', 'user': 'U', 'id': 'E'}
我的代碼是未來：
class User(Base):
__tablename__ = 'user'
id = Column(String, primary_key=True)
def __init__(self, id):
self.id = id
class Item(Base):
__tablename__ = 'item'
id = Column(String, primary_key=True)
def __init__(self, id):
self.id = id
class Event(Base):
__tablename__ = 'event'
id = Column(String, primary_key=True)
user = Column(String, ForeignKey('user.id'))
item = Column(String, ForeignKey('item.id'))
def __init__(self, id, user_id, item_id):
self.id = id
self.user = user_id
self.item = item_id
我使用PostgreSQL作爲後端。
Base.metadata.create_all(engine)
Session = sessionmaker(bind=engine)
session = Session()
usr = User('U')
it = Item('I')
event = Event('E', usr.id, it.id)
session.add(usr)
session.add(it)
session.add(event)