Question

我有一张叫做账单的桌子。法案有多个赞助商和多个共同赞助商。赞助商和共同赞助商都包含一份国会议员名单。我还有一张叫做congress_people的桌子。在congress_people显示页面上，我想显示一张表格，其中显示了国会议员赞助的票据以及显示他们共同发行的票据的票据。有关如何做到这一点的任何想法？我知道生成表格，但我不知道如何设置关联。我正在使用rails 4.2和mysql2。感谢

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

这将允许您拨打以下电话：

@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CongressPerson节目视图中

<%= @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 %>

设置关联/ db引用rails 4

1 个答案: