我如何摧毁一个加载ActiveModel实例与相关的破坏有一个默认的排序孩子吗？ [英] How do I destroy a ActiveModel instance with dependant destroy children that have a default ordering?

问题描述

在Rails 4.0我有2 ActiveRecord的类：

In Rails 4.0 I have 2 ActiveRecord classes:

class Sequence < ActiveRecord::Base

    has_many :steps, dependent: :destroy

end

和

class Steps < ActiveRecord::Base

    belongs_to :sequence

    default_scope -> { order('order ASC') }

end

当我称之为 mySequence.destroy 我得到这个错误：

When I call mySequence.destroy I get this error:

PG ::语法错误：错误：语法错误或接近订单行1：...步骤WHERE步骤sequence_id= $ 1 ORDER BY为了ASC ^：选择。。* FROM的步骤步骤WHERE台阶。sequence_id= $ 1目承ASC

PG::SyntaxError: ERROR: syntax error at or near "order" LINE 1: ...steps" WHERE "steps"."sequence_id" = $1 ORDER BY order ASC ^ : SELECT "steps".* FROM "steps" WHERE "steps"."sequence_id" = $1 ORDER BY order ASC

当我删除默认的范围，错误走了，但我明明已经下令在我的code在序列中的步骤。 我曾尝试这样定义的关联，并留下了default_scope语句：

When I remove the default scope, the error is gone, but I obviously have to order the steps in my sequence in my code. I did try to define the association like this, and leaving out the default_scope statement:

class Sequence < ActiveRecord::Base

    has_many :steps, dependent: :destroy, order: 'order ASC'

end

但它抛出了同样的错误。

but it threw the same error.

没有任何人有这个问题？这是Rails中的错误？我想象中的排序不需要在对孩子的破坏SQL语句。

Does anyone else have this issue? Is this a bug in Rails? I imagine the ordering is not needed in the destroy sql statement on the children.

推荐答案

我贴这个问题上轨GitHub的问题页面上也是如此。 GitHub的用户tanraya 建议采取以下优雅的解决方案。

I posted this issue on the rails gitHub issue page as well. gitHub user tanraya suggested the following elegant solution.

default_scope -> { order order: :asc }

由于从看过来，tanraya和赞誉！

Thanks from over here, tanraya, and kudos!

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