ruby-on-rails - 如何获得强参数以允许嵌套的 fields_for 属性？

Question

我有一个带有嵌套 fields_for 的表单。我试图允许由该嵌套表单生成的参数，但它们被强参数阻止了。我正在使用 rails 4.2.4 和 ruby​​ 2.2.2

我看过一些官方文档:

• http://api.rubyonrails.org/classes/ActionController/StrongParameters.html
• http://guides.rubyonrails.org/action_controller_overview.html#strong-parameters

我已经阅读了相关的 SO 帖子:

• Rails 4 Nested Attributes Unpermitted Parameters
• How to permit strong params for nested attributes?

我阅读了各种博客文章:

• http://www.rubyexperiments.com/using-strong-parameters-with-nested-forms/
• http://adamyonk.com/2013/05/16/rails-4-strong-parameters-and-nested-forms.html
• 还有更多

我想我是按照他们说的去做，但是我的嵌套属性被强参数拒绝了。我在日志中得到类似 Unpermitted parameters: __template_row__, 0, 1, 2, 3 的内容。

这是我的代码:

models/enclosure.rb

class Enclosure < ActiveRecord::Base
  has_many :resident_animals, -> { order("year DESC, month DESC") }, dependent: :restrict_with_error
  validates :name, presence: true, uniqueness: {case_sensitive: false}

  accepts_nested_attributes_for :resident_animals, allow_destroy: true, reject_if: :all_blank

  def to_s
    name
   end
end

models/resident_animal.rb

class ResidentAnimal < ActiveRecord::Base
  belongs_to :enclosure

  validates_presence_of :enclosure, :year, :month, :color
  ...
end

controllers/enclosures_controller.rb

class EnclosuresController < ApplicationController
  ...
  def update
    @enclosure = Enclosure.find(params[:id])
    @enclosure.update(enclosure_params)
    respond_with @enclosure
  end

  private

  def enclosure_params
    params.require(:enclosure).permit(:name, :description, resident_animals_attributes: [:year, :month, :color, :id, :_destroy])
  end
end

views/enclosures/_form.html.erb

<p class="field">
  <%= form.label :name %>
  <%= form.text_field :name %>
</p>

<p class="field">
  <%= form.label :description %>
  <%= form.text_area :description %>
</p>

<fieldset>
  <legend>Resident Animals</legend>

  <table id="resident-animal-rows">
    <thead>
      <th>Year <span class="required-field">*</span></th>
      <th>Month <span class="required-field">*</span></th>
      <th>Color <span class="required-field">*</span></th>
      <th>Remove</th>
    </thead>
    <tbody>
      <%= form.fields_for :resident_animals_attributes, ResidentAnimal.new(channel: form.object, year: Date.current.year, month: Date.current.month), index: "__template_row__" do |resident_animal_fields| %>
      <tr class="resident-animal-row row-template">
        <td><%= resident_animal_fields.number_field :year %></td>
        <td><%= resident_animal_fields.select :month, month_options, include_blank: true %></td>
        <td><%= resident_animal_fields.text_field :color %></td>
        <td class="checkbox-cell"><%= resident_animal_fields.check_box :_destroy %></td>
      </tr>
      <% end %>
      <%= form.fields_for :resident_animals do |resident_animal_fields| %>
        <tr class="resident-animal-row">
          <td><%= resident_animal_fields.number_field :year %></td>
          <td><%= resident_animal_fields.select :month, month_options, include_blank: true %></td>
          <td><%= resident_animal_fields.text_field :color %></td>
          <td class="checkbox-cell">
            <%= resident_animal_fields.hidden_field :id %>
            <%= resident_animal_fields.check_box :_destroy %>
          </td>
        </tr>
      <% end %>
    </tbody>
  </table>
  <%= link_to "Add resident animal", "#", class: "resident-animal-row-add" %>
</fieldset>

当我记录我的参数时，它们看起来像:

{"enclosure"=>{"name"=>"Polar Quest", "description"=>"Polar bear attraction", "resident_animals_attributes"=>{"__template_row__"=>{"year"=>"2015", "month"=>"9", "color"=>"", "_destroy"=>"0"}, "0"=>{"year"=>"2005", "month"=>"8", "color"=>"white", "id"=>"1", "_destroy"=>"0"}, "1"=>{"year"=>"2012", "month"=>"7", "color"=>"yellow", "id"=>"2", "_destroy"=>"0"}, "2"=>{"year"=>"2011", "month"=>"3", "color"=>"white", "id"=>"4", "_destroy"=>"0"}, "3"=>{"year"=>"2006", "month"=>"2", "color"=>"yellowish", "id"=>"3", "_destroy"=>"0"}}}, "commit"=>"Update", "id"=>"1"}

调用 enclosure_params 返回:

{"name"=>"Polar Quest", "description"=>"Polar bear attraction", "resident_animals_attributes"=>{}}

我做错了什么？

Answer 1

谢谢!

我将从您的评论中添加正确的答案，这样这个问题就有了正确的答案:

问题是 .permit 嵌套散列，其中包括 ID 作为键和其他属性的散列作为值是一种特殊情况(很明显，因为它没有匹配 .permit 的典型参数结构)。

诀窍是:当且仅当所有键都翻译到整数!因此，如果键集中有非整数值(例如 __template_row__ 或 new_record_id)，它不会检测特殊情况，而是拒绝每个键在未明确允许的哈希中(对于任何典型的哈希)。

为了解决这个问题，鉴于原始帖子中的参数结构，您可以简单地删除作为模板行的一部分提交的非整数键和属性:

def enclosure_params
  params[:enclosure][:resident_animals_attributes].delete(:__template_row__)
  params.require(:enclosure).permit(...) # (no change from OP)
end

(当然这意味着，您应该确保您的界面不会尝试将有意义的数据作为模板行的一部分提交)；)