Rails 5 ActionCable 从 URL 参数建立流 [英] Rails 5 ActionCable establish stream from URL parameters

问题描述

我对 Rails 几乎完全陌生，或者我相信我自己会知道如何回答这个问题.我只是想修改在基本 ActionCable 演示中创建的基本聊天应用程序:https://medium.com/@dhh/rails-5-action-cable-demo-8bba4ccfc55e#.6lmd6tfi7

I am almost completely new to Rails, or I am sure I would know how to answer this question myself. I am just trying to modify the basic chat app created in the basic ActionCable demo: https://medium.com/@dhh/rails-5-action-cable-demo-8bba4ccfc55e#.6lmd6tfi7

我想拥有多个聊天室，而不是只有一个聊天室，所以我修改了我的 routes.rb，添加了这一行:

Instead of having just one chat room, I want to have multiple chat rooms, so I modified my routes.rb by adding this line:

get '/rooms/show/:topic', to: 'rooms#show'

所以现在我可以根据不同的主题访问不同的聊天室./app/controllers/rooms_controller.rb 中的房间控制器可以毫无问题地处理这些路由:

So now I can visit different chat rooms based on different topics. The rooms controller at /app/controllers/rooms_controller.rb handles these routes with no problem:

class RoomsController < ApplicationController
  def show
    @topic = params[:topic]
    @messages = Message.all
  end
end

但是这个参数没有被传递到 app/channels/room_channel.rb，我只是不确定我需要做哪些修改.我目前的尝试:

But this parameter is not being passed to app/channels/room_channel.rb, and I'm just not sure what modifications I need to make. My current attempt:

class RoomChannel < ApplicationCable::Channel
  def subscribed
    stream_from "room_channel_#{params[:topic]}"
  end

只返回room_channel_"

only returns "room_channel_"

推荐答案

这里的问题是我无法理解从哪里调用订阅的方法，因此不知道如何将参数传递给它.

The problem here was that I failed to understand from where the subscribed method was being called, and thus did not know how to pass parameters to it.

通过阅读 actioncable 文档:https://github.com/rails/rails/tree/master/actioncable

By reading the actioncable documentation: https://github.com/rails/rails/tree/master/actioncable

我发现订阅的方法是通过客户端 javascript 调用的，而不是通过 rails 控制器调用的.在示例聊天应用程序的情况下，这意味着我必须更改文件 /app/assets/javascripts/channels/room.coffee

I found out that the subscribed method is called via client-side javascript, not by the rails controller. In the case of the example chat app, this means I had to change the first line of the file /app/assets/javascripts/channels/room.coffee

App.room = App.cable.subscriptions.create "RoomChannel",

到

App.room = App.cable.subscriptions.create { channel: "RoomChannel", topic: topic},

将 javascript 对象传递给此方法允许我在 rooms_controller.rb 的 subscribed 方法中访问这些参数.

Passing a javascript object to this method allowed me to access those parameters in the subscribed method of rooms_controller.rb.

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