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我认为我的意图最好用一个简单的例子来解释。让我们说，我有三个值（同一模型的所有对象，比如Users），＆＃34;彼得＆＃34;，＆＃34;约翰＆＃34;和＆＃34; Thurse＆＃34;。我希望我的表单包含两个字段:regular_user和:commander_user。对于这两个字段，我想从模型User中进行选择（因此，select_tags都应包含相同的值 - Peter，John和Thurse）。所以我的目标是为常规用户选择彼得和约翰，为指挥官选择Thurse。另外，我们假设表单适用于模型Game。在这种情况下，绑定模型将是GameUser。基本上我想要的是致电my_game.regular_users并接收＆＃34;彼得＆＃34;和＆＃34;约翰＆＃34;并致电my_game.commanders并接收＆＃34; Thurse＆＃34;。

我的实际结构的字描述如下：我有菜单（如在餐馆），每个菜单可以有不同数量的人。此模型名为Personamount，它们通过Menupersonamount和has_many through关系连接。

适用于一个领域。但我需要以相同的形式保存Personamount中的一些不同条目。

以下是代码：

形式：

 .row
      .col-md-12
            / Select for how many persons this menu can be bought for
            .section.row
              %label.field.prepend-field
                =f.collection_select(:personamount_ids, Personamount.all, :id, :title, {include_blank: false, :include_hidden => false, :selected => @menu.personamounts.map(&:id)}, { class: 'select2-multiple form-control select-info select-personamount', :multiple => true})

        .row
          .col-sm-12
            .section.row
              %label.field.prepend-field
                =f.collection_select(:bonus_personamount_ids, Personamount.all, :id, :title, {include_blank: false, :include_hidden => false}, { class: 'select2-multiple form-control select-info select-bonus-personamount', :multiple => true})

Menu.rb：

class Menu < ActiveRecord::Base
  has_many :menupersonamounts, dependent: :destroy
  has_many :personamounts, through: :menupersonamounts
  has_many :bonus_personamounts, through: :menupersonamounts, :class_name  => "Personamount", :foreign_key => :bonus_personamount_id
end

Menupersonamount.rb：

class Menupersonamount < ApplicationRecord
  belongs_to :menu
  belongs_to :personamount, :class_name  => "Personamount", :foreign_key => :personamount_id
  belongs_to :bonus_personamount, :class_name  => "Personamount", :foreign_key => :bonus_personamount_id
end

Personamount.rb：

class Personamount < ApplicationRecord
    has_many :menupersonamounts, dependent: :destroy
  has_many :menus, through: :menupersonamounts

  has_many  :dinner_amount_options, dependent: :destroy
  accepts_nested_attributes_for :dinner_amount_options, allow_destroy: true
end

这是我的错误：

ActiveRecord::InvalidForeignKey (PG::ForeignKeyViolation: ERROR:  insert or update on table "menupersonamounts" violates foreign key constraint "fk_rails_d94bf3abd0"
DETAIL:  Key (bonus_personamount_id)=(13) is not present in table "bonus_personamounts".
: INSERT INTO "menupersonamounts" ("menu_id", "created_at", "updated_at", "bonus_personamount_id") VALUES ($1, $2, $3, $4) RETURNING "id"):

app/controllers/admin/menus_controller.rb:33:in `update'

嗯，显而易见的是，没有表格bonus_personamounts，但如果我将foreign_key_id从bonus_personamount_id更改为personamount_id，表单只会保存两个相同的价值观。

所以，再次 - 我需要将同一个表Personamount中的值保存到一个表单中的两个不同字段中。

更新1：

Menu.rb

class Menu < ActiveRecord::Base
  has_many :menupersonamounts, dependent: :destroy
  has_many :bonusmenupersonamounts, dependent: :destroy, class_name: "Menupersonamount", foreign_key: :bonuspersonamount_id

  has_many :personamounts, through: :menupersonamounts
  has_many :bonuspersonamounts, through: :bonusmenupersonamounts
end

Personamount.rb

class Personamount < ApplicationRecord
    has_many :menupersonamounts, dependent: :destroy
  has_many :bonusmenupersonamounts, :class_name => 'Menupersonamount', :foreign_key => :bonuspersonamount_id

  has_many :menus, through: :menupersonamounts
  has_many :menus, through: :bonusmenupersonamounts

  has_many  :dinner_amount_options, dependent: :destroy
  accepts_nested_attributes_for :dinner_amount_options, allow_destroy: true
end

Menupersonamount.rb

class Menupersonamount < ApplicationRecord
  belongs_to :menu
  belongs_to :personamount
  belongs_to :bonuspersonamount, :class_name  => "Personamount", foreign_key: :bonuspersonamount_id
end

menus_controller.rb

def update
    if @menu.update(menu_params)
        redirect_to edit_admin_menu_path(@menu), method: :get
        flash[:success] = "Updated!"
    else
        render "edit"
    end
end

private

def menu_params
    params.require(:menu).permit(:category_id, :price, :daterange, :hotpic, :remove_hotpic,
        { delivery_ids: [] }, { recipe_ids: [] }, { personamount_ids: [] }, { bonuspersonamount_ids: [] }, { day_ids: [] }, :change_from, 
        :change_to, :description, :has_dessert, :has_breakfast,
  menurecipes_attributes: [:id, :sortable, :menu_id, :recipe_id, :_destroy, recipe_attributes: [:id, :_destroy]]

  )
end

Answer 1

我想我现在明白了这个问题。你有一个类菜单，它有多个Menuspersonamounts。 Menupersonamounts可以容纳一个personamounts和一个bonuspersonamount，如果它们是连续创建的，则没有问题。

它也只适用于一个字段，因为如果设置多个personamounts（例如），则rails会创建n（在示例2中）Menupersonamounts个记录：

Menupersonamounts1: { personamounts: 1 }
Menupersonamounts2: { personamounts: 2 }

现在让我们假设我们提交相同的两个personamounts（1,2）和bonuspersonamount（1）。现在无法确定如何保存：

Menupersonamounts1: { personamounts: 1, bonuspersonamounts: 1 }
Menupersonamounts2: { personamounts: 2 }

或者：

Menupersonamouns1: { personamounts: 1 }
Menupersonamount2: { personamounts: 2, bonuspersonamounts: 1 }

选择的ID越多越好。所以有两种可能性。自己处理id的映射，或者连续处理Menupersonamounts创建，这样就可以选择一个personamount和一个bonuspersonamount。

Rails在同一模型

1 个答案: