当局部变量位于局部变量中时，您将如何远程附加新对象？

Question

在我的对话索引页面中，我可以单击其中一个对话并远程显示该对话的消息。当消息出现时，有一个表单可以在两个用户之间的同一对话中发送另一条消息。以下是我的设置方式：

对话/index.html.haml

- @conversations.each do |conversation|
  = link_to conversation_messages_path(conversation), remote: true do
    = conversation.topic
.col-lg-12
  #messages-index 

消息/_message.html.haml

- @messages.each do |message|
  = message.body
= render 'messages/form'

消息/_form.html.haml

= form_for [@conversation, @message], remote: true do |f|
  = f.text_area :body
  = f.submit "Send"

消息/_index.js.erb

$('#messages-index').empty().append('<%= j render @messages %>')

conversations_controller.rb

class ConversationsController < InheritedResources::Base

  def index
    @conversations = Conversation.all
  end
end

messages_controller.rb

class MessagesController < InheritedResources::Base

    def index
        @conversation = Conversation.find(params[:conversation_id])
        @messages = @conversation.messages
        @message = current_user.messages.build

      respond_to do |format|
        format.js
      end
    end

  def create
    @message = current_user.messages.build(message_params)
    respond_to do |format|
      if @message.save
        format.js
      else
        format.js 
      end
    end
  end

end

我的问题是当我尝试发送消息并将新消息发布到对话中时，如下所示：

消息/_create.js.erb

$('#messages-index').replaceWith('<%= j render partial: "message", locals: {message: @message} %>');

这不起作用，因为它会发送 500 内部错误：

Started POST "/conversations/6/messages" for 127.0.0.1 at 2015-10-19 04:37:34 -0700
Processing by MessagesController#create as JS
  Parameters: {"utf8"=>"✓", "message"=>{"body"=>"dfdfd"}, "commit"=>"Send", "conversation_id"=>"6"}
  User Load (0.5ms)  SELECT  "users".* FROM "users" WHERE "users"."id" = $1  ORDER BY "users"."id" ASC LIMIT 1  [["id", 4]]
   (0.2ms)  BEGIN
  SQL (15.2ms)  INSERT INTO "messages" ("body", "user_id", "created_at", "updated_at") VALUES ($1, $2, $3, $4) RETURNING "id"  [["body", "dfdfd"], ["user_id", 4], ["created_at", "2015-10-19 11:37:34.866111"], ["updated_at", "2015-10-19 11:37:34.866111"]]
   (47.8ms)  COMMIT
  Rendered messages/_message.html.haml (5.7ms)
  Rendered messages/create.js.erb (7.8ms)
Completed 500 Internal Server Error in 88ms (ActiveRecord: 63.6ms)

NoMethodError - undefined method `each' for nil:NilClass:
  app/views/messages/_message.html.haml:1:in `_app_views_messages__message_html_haml___2837667999247155781_70076471170800'
  actionview (4.2.3) lib/action_view/template.rb:145:in `block in render'
  activesupport (4.2.3) lib/active_support/notifications.rb:166:in `instrument'
  actionview (4.2.3) lib/action_view/template.rb:333:in `instrument'
  actionview (4.2.3) lib/action_view/template.rb:143:in `render'
........

那么我怎样才能以正确的方式附加它，以免出现each 错误？

更新

所以我想我必须如何让@messages 超出部分范围。现在是怎么做到的？这就是我的目标：

#messages-index
  - @messages.each do |message|
    = render message

更新 2

所以我成功解决了接收nil和each的消息的问题。我必须做的是将conversation_id 分配给消息，因为它没有发生，但它仍然没有正确附加。我开始认为你不能这样设置。

Answer 1

你像这样渲染局部：

1. render partial: "message", locals: {message: @message}
2. render @messages

但在部分_message.html.haml 中，您使用变量@messages。按照 Rails 约定，您应该在 `_message.html.haml' 中使用 @message。

请注意，放置= render 'messages/form' 并不是一件好事，因为这个部分是针对单个消息呈现的。

---

更新

这就是我的意思：

对话/index.html.haml

- @conversations.each do |conversation|
  = link_to conversation_messages_path(conversation), remote: true do
    = conversation.topic
.col-lg-12
  #messages-index
.col-lg-12
  #new-message-form

消息/_message.html.haml

  = @message.body

消息/_form.html.haml

= form_tag conversation_messages_path(@conversation), remote: true do
  = text_area_tag :body
  = submit_tag "Send"

消息/_index.js.erb

# Render '_message' partial for each message from @messages
$('#messages-index').empty().append('<%= j render @messages %>')

# Render '_form' partial for new message for @conversation
$('#new-message-form').empty().append('<%= j render partial: "form", locals: { conversation: @conversation }) %>')

Answer 2

当您的@messages 是nil 时，就会出现错误。只需在您的app/views/messages/_message.html.haml 中添加一个条件即可检查@messages.nil? 是否存在