sqlalchemy relationship multiple relationships code example

Example 1: sqlalchemy one to many

class Parent(Base):
    __tablename__ = 'parent'
    id = Column(Integer, primary_key=True)
    children = relationship("Child", back_populates="parent")

class Child(Base):
    __tablename__ = 'child'
    id = Column(Integer, primary_key=True)
    parent_id = Column(Integer, ForeignKey('parent.id'))
    parent = relationship("Parent", back_populates="children")

Example 2: sql alchemy query table and include relationship

# joined-load the "orders" collection on "User"
query(User).options(joinedload(User.orders))

# joined-load Order.items and then Item.keywords
query(Order).options(
    joinedload(Order.items).joinedload(Item.keywords))

# lazily load Order.items, but when Items are loaded,
# joined-load the keywords collection
query(Order).options(
    lazyload(Order.items).joinedload(Item.keywords))