118 lines
3.6 KiB
Python
118 lines
3.6 KiB
Python
"""Example code from the ORM Quick Start.
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https://docs.sqlalchemy.org/en/20/orm/quickstart.html
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"""
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from typing import override
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from sqlalchemy import ForeignKey, String, create_engine, select
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from sqlalchemy.orm import DeclarativeBase, Mapped, Session, mapped_column, relationship
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# ------------------------------------------------------------------------------
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# Declare Models
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# ------------------------------------------------------------------------------
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class Base(DeclarativeBase):
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pass
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class User(Base):
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__tablename__: str = "user_account"
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id: Mapped[int] = mapped_column(primary_key=True)
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name: Mapped[str] = mapped_column(String(30))
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fullname: Mapped[str | None] = mapped_column(String, nullable=True)
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addresses: Mapped[list["Address"]] = relationship(
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back_populates="user", cascade="all, delete-orphan"
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)
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@override
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def __repr__(self) -> str:
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return f"User(id={self.id!r}, name={self.name!r}, fullname={self.fullname!r})"
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class Address(Base):
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__tablename__: str = "address"
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id: Mapped[int] = mapped_column(primary_key=True)
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email_address: Mapped[str] = mapped_column(String, nullable=True)
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user_id: Mapped[int] = mapped_column(ForeignKey("user_account.id"))
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user: Mapped["User"] = relationship(back_populates="addresses")
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@override
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def __repr__(self) -> str:
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return f"Address(id={self.id!r}, email_address={self.email_address!r})"
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# ------------------------------------------------------------------------------
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# Create an Engine / Emit CREATE TABLE DDL
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# ------------------------------------------------------------------------------
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engine = create_engine("sqlite://", echo=True)
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Base.metadata.create_all(engine)
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# ------------------------------------------------------------------------------
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# Create Objects and Persist
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# ------------------------------------------------------------------------------
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with Session(engine) as session:
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spongebob = User(
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name="spongebob",
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fullname="Spongebob Squarepants",
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addresses=[Address(email_address="spongebob@sqlalchemy.org")],
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)
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sandy = User(
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name="sandy",
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fullname="Sandy Cheeks",
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addresses=[
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Address(email_address="sandy@sqlalchemy.org"),
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Address(email_address="sandy@squirrelpower.org"),
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],
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)
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patrick = User(name="patrick", fullname="Patrick Star")
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session.add_all([spongebob, sandy, patrick])
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session.commit()
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# ------------------------------------------------------------------------------
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# Simple SELECT / SELECT with JOIN
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# ------------------------------------------------------------------------------
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session = Session(engine)
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stmt = select(User).where(User.name.in_(["spongebob", "sandy"]))
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for user in session.scalars(stmt):
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print(user)
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stmt = (
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select(Address)
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.join(Address.user)
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.where(User.name == "sandy")
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.where(Address.email_address == "sandy@sqlalchemy.org")
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)
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sandy_address = session.scalars(stmt).one()
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print(sandy_address)
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# ------------------------------------------------------------------------------
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# Make Changes / Some Deletes
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# ------------------------------------------------------------------------------
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stmt = select(User).where(User.name == "patrick")
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patrick = session.scalars(stmt).one()
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patrick.addresses.append(Address(email_address="patrickstar@sqlalchemy.org"))
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sandy_address.email_address = "sandy_cheeks@sqlalchemy.org"
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session.commit()
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sandy = session.get(User, 2)
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assert sandy is not None
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sandy.addresses.remove(sandy_address)
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session.flush()
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session.delete(patrick)
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session.commit()
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