sqlalchemy ORM：如何声明包含多列主键的表类？

Question

The columns of the primary key must be in specific order.

I see some code from document :

class User(Base):
    __tablename__ = 'users'

    id = Column(Integer)

    __mapper_args__ = {
        'primary_key':[id]
    }

But it just does not work (I'm using mysql, and the id primary key will not be generated). Any possible solutions?

Answer 1

In case columns are declared in the same order as they should be in the primary key:

class User(Base):
    field1 = Column(Integer, primary_key=True)
    field2 = Column(Integer, primary_key=True)

Otherwise declare it in __table_args__ :

class User(Base):
    field1 = Column(Integer)
    field2 = Column(Integer)
    __table_args__ = (
        PrimaryKeyConstraint('field2', 'field1'),
        {},
    )