Ruby on Rails – 如何从嵌套模型委派错误消息

class User include Mongoid::Document has_many :images accepts_nested_attributes_for :image end class Image include Mongoid::Document include Mongoid::Timestamps include Mongoid::Paperclip has_mongoid_attached_file :uploaded_image, :path => ":rails_root/public/uploads/:class/:id/:basename.:extension", :url => "public/uploads/" validates_attachment_content_type :uploaded_file, :content_type => "application/png", :message => "error massage" belongs_to :user delegate :url, :path, to: :uploaded_image, allow_nil: true, prefix: false end 

如果：uploaded_image无效，如何将Image中的错误委托给用户？

例如：

 user_image = user.images.build(uploaded_image: new_image.path) user_image.save 

如果uploaded_image无效，应该引发错误。

Answer 1

Rails有validates_associated助手（在Mongoid中也可用），它会调用valid? 在每个相关对象上。

validates_associated的默认错误消息是“无效”。 请注意，每个关联对象都将包含自己的错误集合; 错误不会冒泡到调用模型。

Rails指南：活动记录validation

 class User include Mongoid::Document has_many :images accepts_nested_attributes_for :image validates_associated :images end 

请注意 ，您不应将validates_associated :user添加到Image因为它会导致无限循环。

您可以访问嵌套图像的错误，如下所示：

 <% if @user.errors.any? %> 
 
<%= pluralize(@user.errors.count, "error") %> prohibited this user from being saved:
 
 <% @user.errors.full_messages.each do |msg| %> 
<%= msg %>
 <% end %> 
 <% if @user.images.any? %> 
 <% @user.images.each do |image| %> <% if image.errors.any? %> 
 
 <% image.errors.full_messages.each do |msg| %> 
<%= msg %>
 <% end %> 
 
 <% end %> <% end %> 
 <% end %> 
 <% end %>