ruby-on-rails - Rails has_many 通过带有附加属性的表单

Question

我正在尝试创建一个允许用户添加/编辑/删除事件地点的表单。我目前找到的所有示例都是针对 HABTM 表单(不允许编辑 has_many through 配置中存在的附加属性)或仅列出现有的关系。

下面是一张图片，显示了我正在努力完成的事情。

该列表将显示每个可用位置。将检查通过 campaign_locations 模型建立关系的位置，并使它们的 campaign_location 特定属性可编辑。未选中的位置应该能够被选中，输入 campaign_location 特定数据，并在提交时创建新关系。

下面是我目前已经实现的代码。我尝试使用 collection_check_boxes，它非常接近我的需要，只是它不允许我编辑 campaign_location 属性。

我已经能够成功编辑/删除现有的 campaign_locations，但我不知道如何合并它以显示所有可用位置(如附图)。

---

模型

事件.rb

class Campaign < ActiveRecord::Base
  has_many :campaign_locations
  has_many :campaign_products
  has_many :products,  through: :campaign_products
  has_many :locations, through: :campaign_locations

  accepts_nested_attributes_for :campaign_locations, allow_destroy: true
end

campaign_location.rb

class CampaignLocation < ActiveRecord::Base
  belongs_to :campaign
  belongs_to :location
end

位置.rb

class Location < ActiveRecord::Base
  has_many :campaign_locations
  has_many :campaigns, through: :campaign_locations
end

---

查看

事件/_form.html.haml

= form_for @campaign do |campaign_form|

  # this properly shows existing campaign_locations, and properly allows me
  # to edit the campaign_location attributes as well as destroy the relationship
  = campaign_form.fields_for :campaign_locations do |cl_f|
    = cl_f.check_box :_destroy, {:checked => cl_f.object.persisted?}, false, true
    = cl_f.label cl_f.object.location.title
    = cl_f.datetime_field :pickup_time_start
    = cl_f.datetime_field :pickup_time_end
    = cl_f.text_field :pickup_timezone

  # this properly lists all available locations as well as checks the ones
  # which have a current relationship to the campaign via campaign_locations
  = campaign_form.collection_check_boxes :location_ids, Location.all, :id, :title

---

表单 HTML 部分

 <input name="campaign[campaign_locations_attributes][0][_destroy]" type="hidden" value="true" /><input id="campaign_campaign_locations_attributes_0__destroy" name="campaign[campaign_locations_attributes][0][_destroy]" type="checkbox" value="false" />
 <label for="campaign_campaign_locations_attributes_0_LOCATION 1">Location 1</label>
 <label for="campaign_campaign_locations_attributes_0_pickup_time_start">Pickup time start</label>
 <input id="campaign_campaign_locations_attributes_0_pickup_time_start" name="campaign[campaign_locations_attributes][0][pickup_time_start]" type="datetime" />
 <label for="campaign_campaign_locations_attributes_0_pickup_time_end">Pickup time end</label>
 <input id="campaign_campaign_locations_attributes_0_pickup_time_end" name="campaign[campaign_locations_attributes][0][pickup_time_end]" type="datetime" />
 <input id="campaign_campaign_locations_attributes_0_location_id" name="campaign[campaign_locations_attributes][0][location_id]" type="hidden" value="1" />
 <input id="campaign_campaign_locations_attributes_0_pickup_timezone" name="campaign[campaign_locations_attributes][0][pickup_timezone]" type="hidden" value="EST" />

 <input name="campaign[campaign_locations_attributes][1][_destroy]" type="hidden" value="true" /><input id="campaign_campaign_locations_attributes_1__destroy" name="campaign[campaign_locations_attributes][1][_destroy]" type="checkbox" value="false" />
 <label for="campaign_campaign_locations_attributes_1_LOCATION 2">Location 2</label>
 <label for="campaign_campaign_locations_attributes_1_pickup_time_start">Pickup time start</label>
 <input id="campaign_campaign_locations_attributes_1_pickup_time_start" name="campaign[campaign_locations_attributes][1][pickup_time_start]" type="datetime" />
 <label for="campaign_campaign_locations_attributes_1_pickup_time_end">Pickup time end</label>
 <input id="campaign_campaign_locations_attributes_1_pickup_time_end" name="campaign[campaign_locations_attributes][1][pickup_time_end]" type="datetime" />
 <input id="campaign_campaign_locations_attributes_1_location_id" name="campaign[campaign_locations_attributes][1][location_id]" type="hidden" value="2" />
 <input id="campaign_campaign_locations_attributes_1_pickup_timezone" name="campaign[campaign_locations_attributes][1][pickup_timezone]" type="hidden" value="EST" />

 <input name="campaign[campaign_locations_attributes][2][_destroy]" type="hidden" value="true" /><input id="campaign_campaign_locations_attributes_2__destroy" name="campaign[campaign_locations_attributes][2][_destroy]" type="checkbox" value="false" />
 <label for="campaign_campaign_locations_attributes_2_LOCATION 3">Location 3</label>
 <label for="campaign_campaign_locations_attributes_2_pickup_time_start">Pickup time start</label>
 <input id="campaign_campaign_locations_attributes_2_pickup_time_start" name="campaign[campaign_locations_attributes][2][pickup_time_start]" type="datetime" />
 <label for="campaign_campaign_locations_attributes_2_pickup_time_end">Pickup time end</label>
 <input id="campaign_campaign_locations_attributes_2_pickup_time_end" name="campaign[campaign_locations_attributes][2][pickup_time_end]" type="datetime" />
 <input id="campaign_campaign_locations_attributes_2_location_id" name="campaign[campaign_locations_attributes][2][location_id]" type="hidden" value="3" />
 <input id="campaign_campaign_locations_attributes_2_pickup_timezone" name="campaign[campaign_locations_attributes][2][pickup_timezone]" type="hidden" value="EST" />

Answer 1

您遇到的问题是空白位置尚未实例化，因此您的 View 没有任何可构建表单元素的内容。要解决此问题，您需要在 Controller 的 new 和 edit 操作中构建空白位置。

class CampaignController < ApplicationController
  def new
    empty_locations = Location.where.not(id: @campaign.locations.pluck(:id))
    empty_locations.each { |l| @campaign.campaign_locations.build(location: l) }
  end

  def edit
    # do same thing as new
  end
end

然后，在您的edit 和update 操作中，当用户提交表单。

class CampaignController < ApplicationController
  def create
    params[:campaign][:campaign_locations].reject! do |cl|
     cl[:pickup_time_start].blank? && cl[:pickup_time_end].blank? && cl[:pickup_timezone].blank?
    end
  end

  def update
    # do same thing as create
  end
end

此外，我认为您需要一个用于 location_id 的隐藏字段。