SQL Alchemy NULL标识密钥

Question

我定义了表的模型id字段，如下所示：

id = Column(Integer(15, unsigned=True),
               nullable=False,
               server_default='0',
               primary_key=True,
               unique=True,
               autoincrement=True)

并相应地修改了数据库(MySQL)表，但当我创建模型并尝试提交它时(我使用的是SQLalchemy 0.7.8)

m = MyModel(values without defining the id)
session.add(m)
session.commit()

我得到了这个错误

FlushError: Instance <MyModel at 0x4566990> has a NULL identity key. 
If this is an auto-generated value, check that the database table 
allows generation of new primary key values, and that the mapped 
Column object is configured to expect these generated values.  Ensure 
also that this flush() is not occurring at an inappropriate time, such    
as within a load() event.

Answer 1

我使用Postgres 13，ID的类型是UUIT数据类型。我遇到了同样的问题。我已经通过应用server_default解决了这个问题。

class TrafficLightController(Base):
    __tablename__ = 'Tlc'
    id = Column(UUID, primary_key=True, server_default='uuid_generate_v4()')
    type_id = Column('type_id', UUID)
    title = Column('title', String(100))
    gps_x = Column('gps_x', Float)
    gps_y = Column('gps_y', Float)
    hardware_config = Column('hardware_config', JSONB)
    lcu_id = Column('lcu_id', UUID)
    signal_id = Column('signal_id', UUID)

    def __init__(self, type_id, title, gps_x, gps_y, hardware_config, lcu_id, signal_id):
        self.type_id = type_id
        self.title = title
        self.gps_x = gps_x
        self.gps_y = gps_y
        self.hardware_config = hardware_config
        self.lcu_id = lcu_id
        self.signal_id = signal_id

if __name__ == "__main__":
    dbschema = 'asudd'
    engine = create_engine(DB_CONNECTION_STR, connect_args={'options': '-    csearch_path={}'.format(dbschema)})
    Session = sessionmaker(bind=engine)
    Base = declarative_base()
    Base.metadata.create_all(engine)

    session = Session()
    tlc_obj = TrafficLightController("b0322313-0995-40ac-889c-c65702e1841e", "test DK", 35, 45, "{}", None, None)
    session.add(tlc_obj)

Answer 2

我通过删除server_default值解决了这个问题