0
我有一個與自身有多對多關係的模型:一個操作可以被另一個操作或其自身阻止。提交後Flask-SQLAlchemy多對多鄰接列表更改
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
在外殼
然後,從一個新的數據庫:
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)], [])
犯下開關周圍的名單?
記錄查詢,插入查詢的SQLAlchemy發送數據庫似有不妥:
INSERT INTO preventing_operations (prevents_operation_id) VALUES (?)
with values (1,)
當它應該是:
INSERT INTO preventing_operations (prevents_operation_id, preventing_operation_id) VALUES (?)
with values (2, 1)
我在做什麼錯在這裏?我是否錯誤地定義了我的關係?那爲什麼只有我承諾時纔會改變呢?
使用該命令返回'sqlalchemy.exc.ArgumentError:找不到關於Operation.prevents關係的主要連接條件'prevent_operations.preventing_operation_id =:preventing_operation_id_1'涉及本地映射外鍵列的任何簡單相等表達式。確保引用列與ForeignKey或ForeignKeyConstraint關聯,或者在連接條件中使用foreign()註釋進行註釋。爲了允許除'=='以外的比較運算符,該關係可以被標記爲viewonly = True。' – thepandaatemyface
@thepandaatemyface在定位之前,我實際測試了它,這裏是[工作示例](https://github.com/serebrov/ so-questions/blob/master/sql-alchemy/many_many_save_issue.py),你也需要[這個文件](https://github.com/serebrov/so-questions/blob/master/sql-alchemy/base .py)來運行它。只需下載並保存並運行'python many_many_save_issue.py'。我能夠重現並修復您的問題。 –
我用SQLAlchemy測試了它== 1.0.6 –