PostgreSQL的，Rails和：为了=＆GT;问题 [英] PostgreSQL, Rails and :order => problem

问题描述

我在我的ActiveRecord模型以下行：

I have the following line in my ActiveRecord model:

class Record < ActiveRecord::Base
    has_many :users, :through => :record_users, :uniq => true, :order => "record_users.index ASC"

这是为了让我读出record.users在我为了在record_users模型中使用索引字段的方式。

This is intended to enable me to read out record.users in a way that I order using an index field in the record_users model.

现在的问题是，这种失败在PostgreSQL上，出现以下错误：

The problem is that this fails on PostgreSQL with the following error:

ActionView::TemplateError (PGError: ERROR:  for SELECT DISTINCT, ORDER BY expressions must appear in select list

有没有办法解决的声明，使其工作？

Is there a way to fix the statement to make it work?

推荐答案

我想你可以把它在ActiveRecord的一个bug。 PosgreSQL是更严格的比MySQL一点。你可以帮忙ActiveRecord的设立而不是像这样的联想：

I suppose you could call it a bug in ActiveRecord. PosgreSQL is a bit more restrictive than MySQL. You can help out ActiveRecord by setting up the association like this instead:

class Record < ActiveRecord::Base
  has_many :users,
   :through => :record_users,
   :select => 'DISTINCT users.*, record_users.index',
   :order => "record_users.index ASC"

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