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在我的 Rails 应用程序中，我正在创建一个带有 contentEditable div 的表单，因此我必须通过 AJAX“PUT”请求手动将所有数据发送到我的控制器。但是，创建操作不再起作用，并引发此错误：

Started POST "/submissions" for 98.245.21.165 at 2013-09-25 20:57:51 +0000                                                                                                
Processing by SubmissionsController#create as JSON                                                                                                                        
Parameters: {"title"=>"fyc", "content"=>"fuc", "folder_id"=>"1"}                                                                                                        
User Load (80.3ms)  SELECT "users".* FROM "users" WHERE "users"."id" = 1 LIMIT 1                                                                                        
(81.3ms)  SELECT COUNT(*) FROM "submissions" WHERE "submissions"."title" = 'fyc'                                                                                       
Completed 500 Internal Server Error in 181ms                                                                                                                              

NoMethodError (undefined method `each' for nil:NilClass):                                                                                                                 
  app/controllers/submissions_controller.rb:16:in `create'

这是我在提交控制器中的创建操作：

def create 

    ajax_title = params[:title]
    ajax_content = params[:content]
    ajax_folder = params[:folder_id]
    ajax_parent = params[:parent_id]
    ajax_children = params[:children]

    @submissions = Submission.where(title: ajax_title)

    if @submissions.empty?
    @submission = Submission.create({title: ajax_title, content: ajax_content, user_id: current_user.id, folder_id: ajax_folder, parent_id: ajax_parent, children: ajax_children})
    else
        @submissions[0].content = ajax_content
        @submissions[0].save
    end
end

第 16 行，Rails 抛出 NoMethodError，if @submissions.empty?是创建 Submission 实例之后的行。

我唯一的想法是，也许在我将参数放入 ajax_ 变量的顶部，它返回 nil？我扫描了我的路线，可以看到我确实有一个/submissionsPUT 请求，该请求路由到这个创建操作，所以这不是问题。

这是有问题的 AJAX 调用：

$("#save-entry").click(function(){
            $.ajax({
                type: "POST",
                url: "/submissions",
                dataType: "json",
                data: {title: $("#title-create-partial").text(), content: $("#content-create-partial").text(), folder_id: <%= @folder.id %>},
                complete: function(){
                    $.get("/ajax_load_events/", {folder: <%= @folder.id %>}, null, "script");
                }
            });
        });

就像我说的，我使用 HTML5 contentEditable div 进行表单输入，所以据我所知，我不能真正依赖 Rails 为我执行 AJAX 调用。这个错误最近才开始发生，我不确定它是如何开始的。

有任何想法吗？在这一点上我很绝望。

更新这是我的 Submission.rb 模型：

class Submission < ActiveRecord::Base

belongs_to :user
belongs_to :folder
belongs_to :parent, :class_name => 'Submission'
has_many :children, :class_name => 'Submission', :foreign_key => 'parent_id', :order => ('updated_at DESC')

attr_accessible :content, :title, :user_id, :folder_id, :parent_id, :children

def self.search(search)
  if search
      where('name LIKE ?', "%#{search}%")
  else
      scoped
  end
end

def attributes_with_children
  attributes.merge(children: children.map(&:attributes_with_children))
end

end

还有我的 Folder.rb 模型：

class Folder < ActiveRecord::Base
attr_accessible :title, :user_id, :parent_id

belongs_to :user
belongs_to :parent, :class_name => 'Folder'
has_many :children, :class_name => 'Folder', :foreign_key => 'parent_id'
has_many :submissions, :order => ('updated_at DESC')

def self.search(search)
where("title like ?", "%#{search}%")
end

end
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1 回答 1

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因为submission has_many children那时

Submission.create(:children => nil)会抛出以下错误，因为它需要一个数组children

NoMethodError: You have a nil object when you didn't expect it!
You might have expected an instance of Array.
The error occurred while evaluating nil.each

但是Submission.create(:children => [])不会抛出错误。

在您的示例params[:children]中是nil，因此它会引发错误。所以在控制器中你可以做

ajax_children = Array(params[:children])
#=> [] if params[:children] is nil

这将转换nil为[]并且如果参数是[1,2,3]它保持不变。

通常，请确保传递给模型方法的值在控制器中采用正确的格式，因为用户输入可能会有很大差异。

于 2013-09-25T21:44:17.253 回答