问未定义的方法`__metadata‘当我试图使用mongoid更新带有嵌入式文档的用户时，在Rails 4中设计

EN

Request

Parameters:

{"utf8"=>"✓",
 "_method"=>"put",
 "authenticity_token"=>"auxoUaTmvkvRvLUUh3kUP0lzYo9aTotajjYVfy01OE0=",
 "user"=>{"first_name"=>"Fabian",
 "last_name"=>"Jara",
 "email"=>"admin@example.com",
 "age"=>"35",
 "position_primary"=>"54ed0c136c6f6337ff0a0000",
 "position_secundary"=>"54ed0c136c6f6337ff0a0011"},
 "commit"=>"Update"}

class User
  include Mongoid::Document
  include Mongoid::Timestamps
  include User::AuthDefinitions
  include User::Roles
  include Mongoid::Paperclip

  has_many :identities

  embeds_one :position_primary, class_name: "Position"
  embeds_one :position_secundary, class_name: "Position"

  accepts_nested_attributes_for :position_primary, :position_secundary

  has_mongoid_attached_file :image

  validates_attachment_content_type :image, :content_type => ["image/jpg", "image/jpeg", "image/png", "image/gif"]

  field :first_name, type: String
  field :last_name, type: String
  field :roles_mask, type: Integer
  field :age, type: Integer

end

class Position
    include Mongoid::Document

    field :name, type: String
    field :status, type: Boolean

    embedded_in :users
end

<h2>Edit <%= resource_name.to_s.humanize %></h2>
<%= simple_form_for(resource, :as => resource_name, :url => registration_path(resource_name), :html => { :method => :put, :class => 'form-vertical' }) do |f| %>
  <%= f.input :first_name, :autofocus => true %>
  <%= f.input :last_name %>
  <%= f.input :email, :required => true %>
  <%= f.input :age %>
  <%= f.file_field :image %> <br>

  <%= f.select :position_primary, Position.all.collect {|p| [ p.name, p.id ] }, :prompt => "Select a position" %>
  <br>

  <%= f.select :position_secundary, Position.all.collect {|p| [ p.name, p.id ] }, :prompt => "Select a position" %>
<br>
  <% if current_user.password_required? %>
    <%= f.input :password, :autocomplete => "off", :hint => "leave it blank if you don't want to change it", :required => false %>
    <%= f.input :password_confirmation, :required => false %>
    <%= f.input :current_password, :hint => "we need your current password to confirm your changes", :required => true %>
  <% end %>
  <%= f.button :submit, 'Update', :class => 'btn-primary' %>
<% end %>
<h3>Cancel my account</h3>
<p>Unhappy? <%= link_to "Cancel my account", registration_path(resource_name), :data => { :confirm => "Are you sure?" }, :method => :delete %>.</p>

class Users::RegistrationsController < Devise::RegistrationsController
  before_filter :resource_params, if: :devise_controller?

  def resource_params
    devise_parameter_sanitizer.for(:sign_up) {|user| user.permit(:first_name, :last_name, :email, :password, :password_confirmation)}
    devise_parameter_sanitizer.for(:account_update) {|user| user.permit(:first_name, :last_name, :email, :password, :password_confirmation, :current_password)}
  end

  def update
    authorize! :update, @user, :message => 'Not authorized as an administrator.'
    respond_to do |format|

      if @user.update_attributes(user_params)
        format.html { redirect_to @user, notice: 'User was successfully updated.' }
      else
        format.html { render action: 'edit' }
      end
    end
  end

  # Never trust parameters from the scary internet, only allow the white list through.
  def user_params
    params.require(:user).permit(:email, :first_name, :last_name, :image, :age, :position_primary, :position_secundary, :roles => [])
  end

  private :resource_params
end