ruby-on-rails - Rails 4 嵌套表单，带有 has_many、through 和 multiple select

Question

我对嵌套形式和 has_many 关系有疑问。商业案例:有实验室及其供应商。供应商可以在实验室之间共享。

模型

class Lab < ActiveRecord::Base
  has_many :lab_suppliers
  has_many :suppliers, through: :lab_suppliers
  accepts_nested_attributes_for :lab_suppliers
end

class Supplier < ActiveRecord::Base
  has_many :lab_suppliers
  has_many :labs, through: :lab_suppliers
  accepts_nested_attributes_for :lab_suppliers
end

class LabSupplier < ActiveRecord::Base
  belongs_to :lab
  belongs_to :supplier

  accepts_nested_attributes_for :lab
  accepts_nested_attributes_for :supplier
end

表单

<%= form_for(@lab) do |f| %>
  <div class="field">
    <%= f.label :code %><br>
    <%= f.text_field :code %>
  </div>
  <div class="field">
    <%= f.label :name %><br>
    <%= f.text_field :name %>
  </div>
  <div class"field">
    <%= fields_for :lab_suppliers do |ff| %>
      <%= ff.label :supplier_id %><br>
      <%= ff.collection_select :supplier_id, Supplier.all, :id, :name,  {include_blank: true}, {:multiple => true, :class=>""} %> 
    <% end %>
  </div>
  <div class="actions">
    <%= f.submit %>
  </div>
<% end %>

Controller

class LabsController < ApplicationController
  before_action :set_lab, only: [:show, :edit, :update, :destroy]

  # GET /labs/new
  def new
    @lab = Lab.new
    @lab.lab_suppliers.build
  end

  # POST /labs
  # POST /labs.json
  def create
    #raise params.inspect

    @lab = Lab.new(lab_params)

    @lab_supplier = @lab.lab_suppliers.new(params[:lab_suppliers])
    @lab_supplier.save
    @lab.save


    private

    def lab_params
      params.require(:lab).permit(:code, :name, lab_suppliers_attributes: [])
    end
end

提交表单后检查参数的结果:

参数:

{"utf8"=>"✓",
 "authenticity_token"=>"...",
 "lab"=>{"code"=>"L01",
 "name"=>"xxx"},
 "lab_suppliers"=>{"supplier_id"=>["",
 "1",
 "3"]},
 "commit"=>"Create Lab"}

提交表单时我收到 ActiveModel::ForbiddenAttributesError 在线:

@lab_supplier = @lab.lab_suppliers.new(params[:lab_suppliers])

我缺少什么才能让它按预期工作？

Answer 1

似乎您需要明确告诉 lab_params 您需要传递来自 lab_suppliers 的哪些属性，例如:

params.require(:lab).permit(:code, :name, lab_suppliers_attributes: [:supplier_id])

试试看，然后告诉我。