ORM 查询指南设置：DML

本页说明了 启用 ORM 的 INSERT、UPDATE 和 DELETE 语句 文档中使用的映射和固定数据，该文档位于 ORM 查询指南 中。

>>> from typing import List
>>> from typing import Optional
>>> import datetime
>>>
>>> from sqlalchemy import Column
>>> from sqlalchemy import create_engine
>>> from sqlalchemy import ForeignKey
>>> from sqlalchemy import Table
>>> from sqlalchemy.orm import DeclarativeBase
>>> from sqlalchemy.orm import Mapped
>>> from sqlalchemy.orm import mapped_column
>>> from sqlalchemy.orm import relationship
>>> from sqlalchemy.orm import Session
>>>
>>>
>>> class Base(DeclarativeBase):
...     pass
>>> class User(Base):
...     __tablename__ = "user_account"
...     id: Mapped[int] = mapped_column(primary_key=True)
...     name: Mapped[str] = mapped_column(unique=True)
...     fullname: Mapped[Optional[str]]
...     species: Mapped[Optional[str]]
...     addresses: Mapped[List["Address"]] = relationship(back_populates="user")
...
...     def __repr__(self) -> str:
...         return f"User(name={self.name!r}, fullname={self.fullname!r})"
>>> class Address(Base):
...     __tablename__ = "address"
...     id: Mapped[int] = mapped_column(primary_key=True)
...     user_id: Mapped[int] = mapped_column(ForeignKey("user_account.id"))
...     email_address: Mapped[str]
...     user: Mapped[User] = relationship(back_populates="addresses")
...
...     def __repr__(self) -> str:
...         return f"Address(email_address={self.email_address!r})"
>>> class LogRecord(Base):
...     __tablename__ = "log_record"
...     id: Mapped[int] = mapped_column(primary_key=True)
...     message: Mapped[str]
...     code: Mapped[str]
...     timestamp: Mapped[datetime.datetime]
...
...     def __repr__(self):
...         return f"LogRecord({self.message!r}, {self.code!r}, {self.timestamp!r})"

>>> class Employee(Base):
...     __tablename__ = "employee"
...     id: Mapped[int] = mapped_column(primary_key=True)
...     name: Mapped[str]
...     type: Mapped[str]
...
...     def __repr__(self):
...         return f"{self.__class__.__name__}({self.name!r})"
...
...     __mapper_args__ = {
...         "polymorphic_identity": "employee",
...         "polymorphic_on": "type",
...     }
>>> class Manager(Employee):
...     __tablename__ = "manager"
...     id: Mapped[int] = mapped_column(ForeignKey("employee.id"), primary_key=True)
...     manager_name: Mapped[str]
...
...     def __repr__(self):
...         return f"{self.__class__.__name__}({self.name!r}, manager_name={self.manager_name!r})"
...
...     __mapper_args__ = {
...         "polymorphic_identity": "manager",
...     }
>>> class Engineer(Employee):
...     __tablename__ = "engineer"
...     id: Mapped[int] = mapped_column(ForeignKey("employee.id"), primary_key=True)
...     engineer_info: Mapped[str]
...
...     def __repr__(self):
...         return f"{self.__class__.__name__}({self.name!r}, engineer_info={self.engineer_info!r})"
...
...     __mapper_args__ = {
...         "polymorphic_identity": "engineer",
...     }

>>> engine = create_engine("sqlite+pysqlite:///:memory:", echo=True)
>>> Base.metadata.create_all(engine)
BEGIN ...
>>> conn = engine.connect()
>>> session = Session(conn)
>>> conn.begin()
BEGIN ...