ActionCable 在操作后显示一个空白页面

Question

我正在关注 Michael Hartl tutorial 关于 Rails 5 ActionCable，以建立一个简单的聊天，但我在 MessageController 中的 create 操作中出现了问题:

  def create
    message = current_user.messages.build(message_params)
    if message.save
      ActionCable.server.broadcast 'room_channel',
                                     content:  message.content,
                                     username: message.user.username
      head :ok
    end
  end

它一直持续到 head :ok，然后显示一个空的 HTML 页面。日志是：

Processing by MessagesController#create as HTML
  Parameters: {"utf8"=>"✓", "authenticity_token"=>"h9UsB78aX8mO8Nyn8eZEUuDzAOxL4V7UCMwNuTfwALliMv7OCkcUIeR4/xXIcvPjwq9H1bphjn6G96G+0VYisw==", "message"=>{"content"=>"oi"}, "commit"=>"Send"}
  User Load (1.2ms)  SELECT  "users".* FROM "users" WHERE "users"."id" = ? LIMIT ?  [["id", 1], ["LIMIT", 1]]
  Message Load (2.1ms)  SELECT  "messages".* FROM "messages" ORDER BY "messages"."created_at" DESC LIMIT ?  [["LIMIT", 50]]
   (0.3ms)  begin transaction
  SQL (9.3ms)  INSERT INTO "messages" ("content", "user_id", "created_at", "updated_at") VALUES (?, ?, ?, ?)  [["content", "oi"], ["user_id", 1], ["created_at", 2016-09-19 02:12:58 UTC], ["updated_at", 2016-09-19 02:12:58 UTC]]
   (9.1ms)  commit transaction
[ActionCable] Broadcasting to room_channel: {:content=>"oi", :username=>"alice"}
Completed 200 OK in 69ms (ActiveRecord: 22.0ms)


RoomChannel transmitting {"content"=>"oi", "username"=>"alice"} (via streamed from room_channel)
Finished "/cable/" [WebSocket] for 10.0.2.2 at 2016-09-19 02:12:58 +0000
RoomChannel stopped streaming from room_channel

（之后刷新页面，消息正常显示）

为什么会这样？

我的房间频道class:

class RoomChannel < ApplicationCable::Channel
  def subscribed
    stream_from "room_channel"
  end

  def unsubscribed
    # Any cleanup needed when channel is unsubscribed
  end

end

我的room.coffee

App.room = App.cable.subscriptions.create "RoomChannel",
connected: ->
  # Called when the subscription is ready for use on the server

disconnected: ->
  # Called when the subscription has been terminated by the server

received: (data) ->
  alert data.content

Answer 1

根据建议，我将我为解决此问题所做的工作添加为答案。它没有回答为什么会发生这种情况，而是解决了问题。

解决方法是：移除head :ok。

显然这是不必要的，因为如果我在操作中添加一个测试 whit assert_response :success，它就会通过。

Answer 2

我知道答案已经被接受了，但这个解决方案对我来说很有效，无需删除 head :ok，也许它可以帮助别人。

通常在开发环境中，人们运行 localhost:3000 但我运行在不同的端口，localhost:3030。

在这种情况下，我必须为该端口添加一个允许的请求来源，如下所示：

config.action_cable.allowed_request_origins = [
      'http://localhost:3030'
  ]

给我的 /config/environments/development.rb

Answer 3

我正在学习 Michael 的 ActionCable 教程，但遇到了同样的问题。我认为这是由于格式部分 _anything.html.erb.

app/views/messages/_message_form.html

在学习本教程时，您将升级到 Action Cable 功能。但是在_message_form部分，还是和通常的HTTP request一样。因此，在您使用 messages_controller.rb 广播消息后，浏览器呈现一个空页面，因为表单已经呈现。

app/views/messages/_message_form.html, 原:

<div class="message-input">
  <%= form_for(@message) do |f| %>
    <%= f.text_area :content %>
    <%= f.submit "Send" %>
  <% end %>
</div>

因此，您必须将 remote: true 添加到表单中，如下所示：

<div class="message-input">
  <%= form_for(@message, remote: true) do |f| %>
    <%= f.text_area :content %>
    <%= f.submit "Send" %>
  <% end %>
</div>

添加 remote: true 发出 JS 请求（Ajax，在本例中）

引用迈克尔的话：

You can verify by submitting a message that it appears as desired, but in fact this is a cheat because the form from Listing 6 is currently submitting an ordinary HTTP POST request, which causes the page to refresh. In order to use Action Cable, we need to change the form to submit a remote request that submits an Ajax request without refreshing the page. We can do this by including the remote: true option in the call to form_for.

请注意，我所做的一切都是在 localhost:3000

ActionCable 在操作后显示一个空白页面

ActionCable displays an empty page after action

ruby-on-rails

actioncable