我正在尝试创建一个表单，允许用户向活动添加/编辑/删除位置。我目前找到的所有例子要么是HABTM表单（不允许编辑存在于表单中的附加属性）has_many through配置）或仅列出现有关系。

下面的图片显示了我想要完成的任务。

该列表将显示每个可用位置。通过campaign_locations模型有关系的位置将被检查，并且其campaign_location特定属性可编辑。未检查的位置应该能够被检查，输入campaign_location特定数据，并在提交时创建新的关系。

下面是我目前已经实现的代码。我尝试过利用collection_check_boxes，这非常接近我所需要的，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，但我不知道如何将其合并以显示所有可用位置（如附图）。

Models

活动.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

活动地点.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

View

活动/_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 的一部分

 <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" />

您遇到的问题是空白位置尚未实例化，因此您的视图无法为其构建表单元素。要解决此问题，您需要在控制器中构建空白位置new and edit行动。

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，在你的edit and update操作中，您需要删除所有留空的位置params用户提交表单时的哈希值。

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

另外，我认为你需要一个隐藏字段location_id.