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我有一个与自身有多对多关系的模型:一个操作可以被另一个操作或其自身阻止。提交后Flask-SQLAlchemy多对多邻接列表更改
operation_to_operation_association_table = db.Table(
"preventing_operations",
db.Column("id", db.Integer, primary_key=True),
db.Column("preventing_operation_id", db.Integer, db.ForeignKey("operation.id")),
db.Column("prevents_operation_id", db.Integer, db.ForeignKey("operation.id")))
class Operation(BaseModel): # BaseModel defines id and creation/update times
name = db.Column(db.String)
bodypart_id = db.Column(db.Integer, db.ForeignKey(BodyPart.id))
bodypart = db.relationship("BodyPart", backref="operations")
prevents = db.relationship("Operation", secondary=operation_to_operation_association_table,
foreign_keys=[operation_to_operation_association_table.c.preventing_operation_id],
backref="prevented_by")
def __eq__(self, other):
return other and self.name == other.name and self.bodypart == other.bodypart
在外壳
然后,从一个新的数据库:
In [1]: bp = BodyPart(name="liver")
In [2]: db.session.add(bp)
In [3]: db.session.commit()
In [4]: o1, o2 = Operation(name="viewing", bodypart=bp), Operation(name="removing", bodypart=bp)
In [5]: db.session.add_all([o1, o2])
In [6]: db.session.commit()
In [7]: o1, o2
Out[7]: (Viewing the liver (1), Removing the liver (2))
In [8]: o1.prevents, o2.prevents
Out[8]: ([], [])
In [9]: o2.prevents.append(o1)
In [10]: o1.prevents, o2.prevents
Out[10]: ([], [Viewing the liver (1)])
In [11]: db.session.commit()
In [12]: o1.prevents, o2.prevents
Out[12]: ([Viewing the liver (1)], [])
犯下开关周围的名单?
记录查询,插入查询的SQLAlchemy发送数据库似有不妥:
INSERT INTO preventing_operations (prevents_operation_id) VALUES (?)
with values (1,)
当它应该是:
INSERT INTO preventing_operations (prevents_operation_id, preventing_operation_id) VALUES (?)
with values (2, 1)
我在做什么错在这里?我是否错误地定义了我的关系?那为什么只有我承诺时才会改变呢?
使用该命令返回'sqlalchemy.exc.ArgumentError:找不到关于Operation.prevents关系的主要连接条件'prevent_operations.preventing_operation_id =:preventing_operation_id_1'涉及本地映射外键列的任何简单相等表达式。确保引用列与ForeignKey或ForeignKeyConstraint关联,或者在连接条件中使用foreign()注释进行注释。为了允许除'=='以外的比较运算符,该关系可以被标记为viewonly = True。' – thepandaatemyface
@thepandaatemyface在定位之前,我实际测试了它,这里是[工作示例](https://github.com/serebrov/ so-questions/blob/master/sql-alchemy/many_many_save_issue.py),你也需要[这个文件](https://github.com/serebrov/so-questions/blob/master/sql-alchemy/base .py)来运行它。只需下载并保存并运行'python many_many_save_issue.py'。我能够重现并修复您的问题。 –
我用SQLAlchemy测试了它== 1.0.6 –