Rails 通过关系在 has_many 中具有嵌套属性的表单

Question

我正在尝试使用 has_many :through 关系中的多个嵌套对象构建表单。但是，嵌套对象在保存时似乎没有被分配父对象的 foreign_key。我不确定我在这里做错了什么。

# app/models/admin/host.rb
class Admin::Host < ApplicationRecord
  has_many :admin_host_users, class_name: 'Admin::HostUser', foreign_key: 'admin_host_id', dependent: :destroy
  has_many :users, through: :admin_host_users

  accepts_nested_attributes_for(:admin_host_users, allow_destroy: true)

# app/models/admin/host_user.rb
class Admin::HostUser < ApplicationRecord
  belongs_to :admin_host, class_name: 'Admin::Host'
  belongs_to :user

# app/models/user.rb
class User < ApplicationRecord
  has_many :admin_host_users, class_name: 'Admin::HostUser'
  has_many :admin_hosts, through: :admin_host_users

# app/controllers/hosts_controller.rb
class HostsController < ApplicationController
  def create
    @host = Admin::Host.new(admin_host_params.merge(status: :pending))
    @host.save!
  end

  def new
    @host = Admin::Host.new
    @admin_host_users = [@host.admin_host_users.build(user: current_user)]
  end

  private
  
  def admin_host_params
    params.require(:admin_host).permit(
      :name,
      admin_host_users_attributes: [
        :user_id,
        :role,
      ],
    )
  end

# app/views/hosts/_form.html.erb
<%= form_with(model: @host, url: hosts_path, local: true) do |f| %>
  <% @admin_host_users.each do |admin_host_user| %>
    <%= f.fields_for(:admin_host_users, admin_host_user) do |admin_host_user_form| %>
      <%= admin_host_user_form.select(:user_id, @all_users) %>

好的，这就是代码。这是提交表单时的回复：

Started POST "/hosts" for ::1 at 2021-05-23 08:45:22 -0400
Processing by HostsController#create as HTML
  Parameters: {"utf8"=>"✓", "admin_host"=>{"name"=>"Test", "admin_host_users_attributes"=>{"0"=>{"user_id"=>"1"}}}, "commit"=>"Apply Now"}

Completed 422 Unprocessable Entity in 287ms (ActiveRecord: 42.5ms)

ActiveRecord::RecordInvalid (Validation failed: Admin host users admin host must exist):
  
app/controllers/hosts_controller.rb:10:in `create'

Answer 1

尝试在 has_many 关联上设置 inverse_of 选项

  has_many :admin_host_users, class_name: 'Admin::HostUser', foreign_key: 'admin_host_id', dependent: :destroy, inverse_of: 'Admin::Host'
  has_many :users, through: :admin_host_users, inverse_of: 'Admin::Host'

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