设置关联/数据库引用 rails 4

Question

我有一张名为 bills 的表。比尔有_many 赞助商和has_many 共同赞助商。赞助商和共同赞助商都包含一份国会人员名单。我还有一张名为 congress_people 的桌子。在 congress_people 显示页面上，我想显示一张表格，显示国会人士赞助的账单和显示他们共同赞助的账单的表格。关于我如何做到这一点的任何想法？我知道要生成表格，但我不确定如何设置关联。我正在使用 rails 4.2 和 mysql2。谢谢

Answer 1

您可以使用has_many_through 关联，大致如下：

class Bill < ActiveRecord::Base
  has_many :sponsorships, -> { where(kind: :primary) }, class_name: "Sponsorship"
  has_many :cosponsorships, -> { where(kind: :secondary) }, class_name: "Sponsorship"

  has_many :sponsors, class_name: 'CongressPerson', through: :sponsorships
  has_many :cosponsors, class_name: 'CongressPerson', through: :cosponsorships
end

class Sponsorship < ActiveRecord::Base
  # schema bill_id(INT), sponsor_id(INT), kind(STRING)
  belongs_to :bill
  belongs_to :sponsor, class_name: "CongressPerson"
end

class CongressPerson < ActiveRecord::Base
  has_many :sponsorships, -> { where(kind: :primary) }, class_name: "Sponsorship", foreign_key: :sponsor_id
  has_many :cosponsorships, -> { where(kind: :secondary) }, class_name: "Sponsorship", foreign_key: :sponsor_id

  has_many :sponsored_bills, through: :sponsorships, source: :bill
  has_many :cosponsored_bills, through: :cosponsorships, source: :bill

end

这是Sponsorship 表的基本迁移：

class CreateSponsorships < ActiveRecord::Migration
  def change
    create_table :sponsorships do |t|
      t.references :bill
      t.references :sponsor
      t.string :kind

      t.timestamps
    end
  end
end

这将允许您进行如下调用：

@bill.sponsors
# => returns the congress_people sponsoring the bill

@bill.cosponsors
# => returns the congress_people cosponsoring the bill

@congress_person.sponsored_bills
# => returns the bills sponsored by the congress person

@congress_person.cosponsored_bills
# => returns the bills cosponsored by the congress person

然后在您的CongressPerson 显示视图中：

<%= @congress_person.sponsored_bills.each do |sponsored| %>
  # populate your HTML table row
<% end %>
<%= @congress_person.cosponsored_bills.each do |cosponsored| %>
  # populate your HTML table row
<% end %>