SQLAlchemy 测试数据到关联对象

Question

我正在使用 sqlalchemy 构建数据库，我想测试我的模型。即使我阅读了一些主题并浏览了文档，我也不确定我是否理解如何将数据加载到关联 table 中。我以这种方式创建了两个类 :

class Instance(Base):
    __tablename__ = 'Instances'

    id = Column(Integer, primary_key=True)
    url = Column(String, nullable=False)
    env = Column(String(3), nullable=False)
    code = Column(String, nullable=False) 

    customer = relationship('CustomerInstance', back_populates='instance')


class Customer(Base):
    __tablename__ = "Customers"

    id = Column(Integer, primary_key=True)
    name = Column(String, nullable=False)
    code = Column(String, nullable=False)

    instance = relationship('CustomerInstance', back_populates='customer')

class CustomerInstance(Base):
    __tablename__='Customers_Instances'

    customer_id = Column(Integer, ForeignKey('Customers.id'), primary_key=True)
    instance_id = Column(Integer, ForeignKey('Instances.id'), primary_key=True)

    instance = relationship('Instance', back_populates='customer')
    customer = relationship('Customer', back_populates='instance')

然后我创建我的会话并刷新它：

session = Session()

session.add_all([
    Instance(url='www.web.com', env='prd', code='123'),
    Instance(url='www.123.com', env='prd', code='321'),
    Instance(url='www.qwe.com', env='prd', code='345'),
    Instance(url='www.rty.com', env='prd', code='678'),
    Instance(url='www.hello.com', env='tes', code='098'),
    Instance(url='www.hi.com', env='uat', code='567'),
    Customer(name='ABC', code='567'),
    Customer(name='DEF', code='000'),
    Customer(name='GHI', code='123'),
    Customer(name='KLM', code='456')
])

session.commit()

现在如何填充 object/table CustomerInstance，因为它仅由 2 个 ID 组成？我走的路对吗？同样的问题，如何将数据注入 table 其中 primary_key 是 FK？

Answer 1

要么通过 relationship 分配链接实例，要么发出链接对象的 flush（刷新后，新创建对象的主键被填充）并手动分配 ID .

例子

instance = CustomerInstance(
    instance=Instance(url='example.com', env='prd', code=123),
    customer=Customer(name='ABC', code='123'),
)
session.add(instance)

# SQLAlchemy will handle the foreign keys itself.
session.flush()

或

instance = Instance(url='example.com', env='prd', code=123),
customer = Customer(name='ABC', code='123'),
session.add_all([instance, customer])
session.flush()

# Now the primary keys are populated!
cust_instance = CustomerInstance(
    customer_id=customer.id,
    instance_id=instance.id,
)

SQLAlchemy 测试数据到关联对象

SQLAlchemy testing data to associative object

database

sqlalchemy

associative-table

例子