Question

生成新频道时，会注释掉stream_from方法调用。我理解，它适合识别流，例如stream_from＆＃34; comments _＃{message.id}＆＃34;。

但是如果这个频道没有这样的目标并且应该流式传输所有评论？什么是此通道的默认行为（可能是值）而未指定stream_from？

Answer 1

假设您的频道名为SomethingChannel

class SomethingChannel < ApplicationCable::Channel
  def subscribed
    # because you do not need stream_from, then remove the stream_from below
    # stream_from "something_channel"

    # and just immediately transmit the data. This should be a hash, and thus I use `as_json`; Change this accordingly as you see fit
    transmit(Comment.all.as_json)
  end

  def unsubscribed
    # Any cleanup needed when channel is unsubscribed
  end
end

然后在客户端，您只需在需要时调用以下内容。

# ...coffee
App.cable.subscriptions.create 'SomethingChannel',
  connected: ->
    console.log('connected')

  # Called when the WebSocket connection is closed.
  disconnected: ->
    console.log('disconnected')

  # `transmit(Comment.all.as_json)` above will invoke this
  received: (data) ->
    console.log('received')
    console.log(data)

您应该会在Google Chrome / Firefox控制台中看到以下内容：

connected
received
▼ [{…}]
  ▶ 0: {id: 1, title: "Hello ", content: "World from Earth! :)", created_at: "2018-02-13T16:15:05.734Z", updated_at: "2018-02-13T16:15:05.734Z"}
  ▶ 1: {id: 2, title: "Lorem ", content: "Ipsum Dolor", created_at: "2018-02-13T16:15:05.734Z", updated_at: "2018-02-13T16:15:05.734Z"}
  length: 2
  ▶ __proto__: Array(0)

P.S。如果你不能使用stream_from或stream_for，那么也许你可能不需要ActionCable，也许你最好从API中检索所有的评论相反（即GET /comments）

rails中actioncable的默认行为是什么？

1 个答案: