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我使用两个表的Flask + SQLAlchemy + PostgreSQL。 包含用户的表格和包含目标的表格(用户想要实现的内容)。SQLAlchemy + Flask多对一的关系
models.py:
class User(Base):
__tablename__ = 'users'
id = Column(Integer, primary_key=True)
user_name = Column(Text)
email = Column(String(255), unique=True, nullable=False)
password = Column(String(255))
# A user can only have one goal at a time
goal_id = Column(Integer, ForeignKey('goals.id'))
goal = relationship("Goal", back_populates="user")
class Goal(Base):
""" Goals: Health, Fitness, Wealth, etc. """
__tablename__ = 'goals'
id = Column(Integer(), primary_key=True)
name = Column(String(80), unique=True)
description = Column(String(255))
user = relationship("User", back_populates="goal", uselist=False)
用户只能有一次一个目标。在我的测试情况下,我第一次填充表目标:
tests.py:
for goal in ["Health", "Fitness", "Wealth"]:
session.add(Goal(name=goal))
然后,我希望能够以填充每3个用户提供了不同的目标。什么是实现这个的正确方法?
尝试(简化代码):
user = User()
goal = Goal()
user.goal.append(goal)
给我:
user.goal.append(goal)
E AttributeError: 'NoneType' object has no attribute 'append'
事实上,我错过了uselist =假的地步。所以现在很好。但关于这种关系。你确定吗 ? “我基于http://docs.sqlalchemy.org/en/latest/orm/basic_relationships.html上的关系定义(请参阅:多对一,双向行为..) –
啊是的,我的错误我习惯于使用' backref'而不是'back_populates'。我会更新我的答案 – pech0rin