为什么我的带有 `merge` 的 ActiveRecord 作用域返回一个数组? [英] Why does my ActiveRecord scope with `merge` return an array?

问题描述

我的 Contract 模型有一个作用域，它使用 merge 并返回一个数组，而不是我想要的 ActiveRecord::Relation.

I have a scope on my Contract model that uses merge and returns an array, not an ActiveRecord::Relation as I would like.

是的，我看到它说这是一个 ActiveRecord::Relation，但 Rails 是故意骗你的".但在这种情况下:

Yes, I've seen it said that "It is an ActiveRecord::Relation, but Rails is intentionally lying to you". But in this case:

• 范围使用merge
• 仅当它是链中的最后一个作用域时才有效
• 它返回的对象表示它属于 Array
• 它返回的对象在其祖先中没有任何关于 ActiveRecord 的内容
• 在返回值上调用 ActiveRecord::Relation 方法(如 scoped)会引发 NoMethodError: undefined method 'scoped' for []:Array.

• The scope uses merge
• it only works if it's the last scope in the chain
• The object it returns says it's of class Array
• The object it returns has nothing about ActiveRecord in its ancestors
• Calling ActiveRecord::Relation methods like scoped on the return value raises raises NoMethodError: undefined method 'scoped' for []:Array.

范围在 Contract 上，看起来像

The scope is on Contract and looks something like

scope :hourly, scoped.merge(Division.find_by_name!('Hourly').contracts)

为什么这会返回一个数组?我可以让它返回一个 ActiveRecord::Relation 吗?

Why is this returning an array? Can I get it to return an ActiveRecord::Relation?

推荐答案

参考以上评论.我尝试了一种虚拟关系，我希望你与部门和合同有这种关系.

Ref comments above. I gave this a go with a dummy relationship which I expect you have with Division and Contract.

# app/models/contract.rb

scope :hourly,
  select: 'distinct contracts.*',
  joins: :divisions,
  conditions: {
    "divisions.name" => 'Hourly'
  },
  order: :id

contracts = Contracts.hourly
# => [#<Contract id: 1>, #<Contract id: 2>]

contracts.class
# => #<ActiveRecord::Relation>

contracts.scoped.class
# => #<ActiveRecord::Relation>

contracts.arel
# => #<Arel::SelectManager:0x007fab629f7e90>

contracts.to_a
# => [#<Contract id: 1>, #<Contract id: 2>]

contracts.to_sql
# => SELECT distinct contracts.* FROM `contracts` INNER JOIN `divisions` ON `divisions`.`contract_id` = `contracts`.`id` WHERE `divisions`.`name` = 'Hourly' ORDER BY id

如果这就是您要找的，请告诉我...

Let me know if this is what you were looking for...

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