Rails 嵌套属性形式：创建具有多对多关系的对象时出错

Question

我的项目在以下 class 之间存在多对多关系：

class Project < ApplicationRecord
  has_many :project_software_processes, inverse_of: :project, :dependent => :delete_all
  has_many :software_processes, through: :project_software_processes

  accepts_nested_attributes_for :project_software_processes

  attr_accessor :project_attributes
end

..

class SoftwareProcess < ApplicationRecord
  has_many :project_software_processes
  has_many :projects, through: :project_software_processes
 end

--

class ProjectSoftwareProcess < ApplicationRecord
  belongs_to :software_process
  belongs_to :project
end

- -

我正在使用嵌套表单创建项目实例，以便用户可以根据需要选择任意数量的软件进程：

<div class="field">
  <%= f.label :software_processes %>
  <%= f.fields_for :project_software_processes do |project_software_process|  %>
    <%= project_software_process.select(:software_processes_id, @processes.collect { |s| [s.name, s.id] } ) %>
    <%= project_software_process.link_to_remove "Remove this SoftwareProcess" %>
  <% end %>
  <p><%= f.link_to_add "Add a process", :project_software_processes %></p>
</div>

问题是，当我点击提交时，我收到以下验证消息：

Project software processes software process must exist

我花了一点时间才明白错误的真正含义。我猜它在尝试创建 project software process 的实例时抱怨 software process class 的存在。但是，有项目软件过程的实例，用户甚至可以在select下拉列表中select它们。不确定这是否是问题所在。

这是我的项目控制器的一些片段：

 def create
    @project = Project.new(project_params)
    @project.user = current_user

    respond_to do |format|
      if @project.save
        format.html { redirect_to @project, notice: 'Project was successfully created.' }
        format.json { render :show, status: :created, location: @project }
      else
        @processes = SoftwareProcess.all
        format.html { render :new }
        format.json { render json: @project.errors, status: :unprocessable_entity }
      end
    end
  end

--

def project_params
  params.require(:project).permit(:name, :user_id, project_software_processes_attributes: [:software_process_id, :_destroy])
end

--

这是在参数中发送的内容：

  Parameters: {"utf8"=>"✓", "authenticity_token"=>"[FILTERED]", "project"=>{"name"=>"aas", "project_software_processes_attributes"=>{"1484020859023"=>{"software_processes_id"=>"1", "_destroy"=>"false"}, "1484020859693"=>{"software_processes_id"=>"4", "_destroy"=>"false"}}}, "commit"=>"Create Project"}

Answer 1

问题出在 select 方法的名称上，应该是 software_process_id 而不是 software_processes_id。尝试将其更改为：

<%= project_software_process.select(:software_process_id, @processes.collect { |s| [s.name, s.id] } ) %>

此外，Ryan Bate 的软件现在已经相当过时了，nested_forms gem 也不例外。我见过有人推荐 Cocoon 作为合适的替代品。看看here

干杯。

Rails 嵌套属性形式：创建具有多对多关系的对象时出错

Rails nested attribute form: error when creating an object with a many-to-many relationship

ruby-on-rails

nested-forms