使用两个外键确定范围

Question

我有以下架构：

我希望可以选择为两个foreign_keys（proposals和author_id）调用editor_id以及另外一个（例如author_proposals和editor_proposals我需要选择延迟或急切加载它们（例如User.includes(:proposals)或不加joins）。

更新：

#I have the scopes which is like this:
class User < ActiveRecord::Base
  has_many :author_proposals, class_name: 'Proposal', foreign_key: :author_id
  has_many :editor_proposals, class_name: 'Proposal', foreign_key: :editor_id
end

class Proposal < ActiveRecord::Base
  belongs_to :author, class_name: 'User', foreign_key: :author_id
  belongs_to :editor, class_name: 'User', foreign_key: :editor_id
end

但是我需要一个通用的，它会给我所有的提议（author_proposals和editor_proposals），它也会急切加载它们。我应该使用has_many上的条件吗？

Answer 1

我会做这样的事情：

class User < ActiveRecord::Base
  has_many :authored_proposals, class_name: 'Proposal', foreign_key: :author_id
  has_many :editored_proposals, class_name: 'Proposal', foreign_key: :editor_id

  def proposals
    Proposal.where('author_id = :id OR editor_id = :id', { id: id }).distinct
  end
end

class Proposal < ActiveRecord::Base
  belongs_to :author, class_name: 'User', foreign_key: :author_id
  belongs_to :editor, class_name: 'User', foreign_key: :editor_id

  def users
    User.where(id: [author_id, editor_id].uniq)
  end
end

Answer 2

您可以执行以下操作：

class User < ActiveRecord::Base
  has_many :authored_proposals, class_name: 'Proposal', foreign_key: :author_id
  has_many :editored_proposals, class_name: 'Proposal', foreign_key: :editor_id

  def proposals
    authored_proposals | editored_proposals
  end
end

class Proposal < ActiveRecord::Base
  belongs_to :author, class_name: 'User', foreign_key: :author_id
  belongs_to :editor, class_name: 'User', foreign_key: :editor_id

  def users
    author | editor
  end
end

您可以通过执行：proposals来加载User.includes(:authored_proposals, :editored_proposals)。这不是纯粹的轨道方式，但对我来说似乎更清洁。

---

---

你也可以这样做：

class User < ActiveRecord::Base
  has_many :authored_proposals, class_name: 'Proposal', foreign_key: :author_id
  has_many :editored_proposals, class_name: 'Proposal', foreign_key: :editor_id

  has_many : proposals, finder_sql: proc { "SELECT * FROM proposals WHERE (proposals.author_id = #{id} or proposals. editor_id = #{id})" }
end

Answer 3

设置您的关联：

class User < ActiveRecord::Base
  has_many :author_proposals, :class_name => "Proposal", :foreign_key => "author_id"
  has_many :editor_proposals, :class_name => "Proposal", :foreign_key => "editor_id"
end

class Proposal < ActiveRecord::Base
  belongs_to :author, :class_name => 'User', :foreign_key => "author_id"
  belongs_to :editor, :class_name => 'User', :foreign_key => "editor_id"
end