SQLAlchemy-连接表的order_by关系 [英] SQLAlchemy - order_by on relationship for join table

问题描述

我正在使用声明性SQLAlchemy，并且有三个模型:Role，Permission和RolePermission.在我的Role模型中，我具有以下内容:

I'm using declarative SQLAlchemy and I have three models: Role, Permission, and RolePermission. In my Role model, I have the following:

class Role(Base):
    name = Column(u'NAME', VARCHAR(50), nullable=False, unique=True)
    permissionLinks = relationship(RolePermission, backref="role", order_by=name)
    permissions = relationship(Permission, backref=backref("roles",
      order_by=name), secondary=RolePermission.__table__,
      order_by=Permission.name)

现在permissions声明可以正常工作，并且与角色关联的权限按照我的期望(按名称)排序.但是，permissionLinks失败，并出现以下错误:

Now the permissions declaration works fine, and the permissions associated with a role come out sorted as I expect (by name). However, permissionLinks fails with the following error:

sqlalchemy.exc.ProgrammingError:(ProgrammingError)('42000'，'[42000] [Microsoft] [ODBC SQL Server驱动程序] [SQL Server]多部分标识符"ROLES.NAME"未绑定.( 4104)(SQLExecDirectW); [42000] [Microsoft] [ODBC SQL Server驱动程序] [SQL Server]语句无法准备.(8180)')u'选择[ROLES_PERMISSIONS].[ROLE_ID]为[ROLES_PERMISSIONS_ROLE_ID] ，[ROLES_PERMISSIONS].[PERMISSION_ID]为[ROLES_PERMISSIONS_PERMISSION_ID]，[ROLES_PERMISSIONS].[IS_DENIED] AS为[ROLES_PERMISSIONS_IS_DENIED] \ nFROM [ROLES_PERMISSIONS] \ nWHERE [ROLES_PERMISSIONS]? ORDER BY [ROLES].[NAME]'(19，)

sqlalchemy.exc.ProgrammingError: (ProgrammingError) ('42000', '[42000] [Microsoft][ODBC SQL Server Driver][SQL Server]The multi-part identifier "ROLES.NAME" could not be bound. (4104) (SQLExecDirectW); [42000] [Microsoft][ODBC SQL Server Driver][SQL Server]Statement(s) could not be prepared. (8180)') u'SELECT [ROLES_PERMISSIONS].[ROLE_ID] AS [ROLES_PERMISSIONS_ROLE_ID], [ROLES_PERMISSIONS].[PERMISSION_ID] AS [ROLES_PERMISSIONS_PERMISSION_ID], [ROLES_PERMISSIONS].[IS_DENIED] AS [ROLES_PERMISSIONS_IS_DENIED] \nFROM [ROLES_PERMISSIONS] \nWHERE [ROLES_PERMISSIONS].[ROLE_ID] = ? ORDER BY [ROLES].[NAME]' (19,)

问题在于Role未加入，因此无法按Role.name进行排序.我尝试指定primaryjoin=id == RolePermission.id1，但这似乎并没有改变任何东西.如何在这种关系上指定联接，以便可以按联接表之一(即Role.name)中的字段排序?

The problem is that Role is not being joined, so it can't sort by Role.name. I tried specifying primaryjoin=id == RolePermission.id1, but that didn't seem to change anything. How can I specify a join on this relationship such that I can sort by a field in one of the joined tables (namely, Role.name)?

推荐答案

我无法使所有这些解决方案正常工作，但是我找到了一种更简单的方法.

I couldn't make any of these solutions work, however I found an easier way.

from sqlalchemy.ext.declarative import declarative_base

class User(Base):
    # ....
    addresses = relationship("Address",
                         order_by="desc(Address.email)",
                         primaryjoin="Address.user_id==User.id")

在这里找到: http://docs.sqlalchemy.org/en/latest/orm /extensions/declarative/relationships.html

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