强参数 has_man 通过

Question

试图找出 setter 不起作用的原因：

class Company < ActiveRecord::Base
  has_many :memberships 
  has_many :users, :through => :memberships, dependent: :destroy

end

class Membership < ActiveRecord::Base
  belongs_to :user
  belongs_to :company

  validates_presence_of :user
  validates_presence_of :company

end

class User < ActiveRecord::Base
  has_many :memberships
  has_many :companies, :through => :memberships, dependent: :destroy
  accepts_nested_attributes_for :companies
end

---

<%= form_for(@user) do |f| %>
  <% if @user.errors.any? %>
    <div id="error_explanation">
      <h2><%= pluralize(@user.errors.count, "error") %> prohibited this user from being saved:</h2>

      <ul>
      <% @user.errors.full_messages.each do |message| %>
        <li><%= message %></li>
      <% end %>
      </ul>
    </div>
  <% end %>

  <div class="field">
    <%= f.fields_for :company do |ff|%>
      <%= ff.label :name %><br>
      <%= ff.text_field :name %>
    <% end %>
  </div>

  <div class="field">
    <%= f.label :name %><br>
    <%= f.text_field :name %>
  </div>
  <div class="actions">
    <%= f.submit %>
  </div>
<% end %>

---

# Never trust parameters from the scary internet, only allow the white list through.
def user_params
  params.require(:user).permit(:name, companies_attributes:[:name])
end

当我这样做时它会起作用：

# Never trust parameters from the scary internet, only allow the white list through.
def user_params
  params.require(:user).permit(:name, company:[:name])
end

所以对我来说不是很清楚，因为文档说当接受_嵌套_attributes_for :companies 时 setter company_attributes 被 ceated

Answer 1

当使用fields_for 和accepts_nested_attributes_for 时，它们需要匹配。见http://apidock.com/rails/ActionView/Helpers/FormHelper/fields_for

您有accepts_nested_attributes_for :companies 但f.fields_for :company 因此断开连接。

所以尝试更改您的表单以包含

<div class="field">
    <%= f.fields_for :companies do |ff|%>
      <%= ff.label :name %><br>
      <%= ff.text_field :name %>
    <% end %>
  </div>

你的 user_params 方法是

def user_params
  params.require(:user).permit(:name, companies_attributes:[:name])
end

这应该会导致它们在companies_attributes 下填充，并且您原来的user_params 方法可以工作。因为fields_for 应该生成user[companies_attributes[id][name]]，因为user has_many companies（你想在要创建的列表中包括多个公司吗？）