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javascript - 无法从 React 前端的 ActionCable 访问数据

问题描述

我正在尝试使用 actioncable 从 rails 后端广播属于某个游戏的消息。

在我的messages_controller 中：

  def create
@game = Game.find(message_params[:game_id])
@message = Message.new(message_params)
if @message.save
  serialized_data = ActiveModelSerializers::Adapter::Json.new(
    MessageSerializer.new(@message)
  ).serializable_hash
  MessagesChannel.broadcast_to @game, serialized_data
  head :ok
end
end

在我的messages_channel中：

  def subscribed
    @game = Game.find(params[:id][:game_id])
    stream_from @game
  end

在前端，我正在使用这个文件：

import ActionCable from 'actioncable';
import { CABLE } from "../constants";

export default function MessagesSubscription(
  game_id,
  { onUpdate = () => {} } = {}
) {
  // 2. Define our constructor
  this.cable = ActionCable.createConsumer(CABLE);
  // this.channel;
  this.game_id = game_id;
  this.onUpdate = onUpdate;

  // 3. Define the function we will call to subscribe to our channel
  this.subscribe = () => {
    console.log("subscribed")
    this.channel = this.cable.subscriptions.create(
      { channel: 'MessagesChannel', id: this.game_id },
      {
        connected: this.connected,
        disconnected: this.disconnected,
        received: this.received,
        rejected: this.rejected,
      }
    );
  };

  // 4. Define our default ActionCable callbacks.
  this.received = (data) => {
    console.log(`Received Data: ${data}`);

    this.onUpdate(data);
  };

  this.connected = () => {
    console.log(`this.connected`);
  };

  this.disconnected = () => {
    console.warn(`this.disconnected.`);
  };

  this.rejected = () => {
    console.warn('I was rejected! :(');
  };
}

问题是在客户端我可以点击连接、断开连接和拒绝，但我不能点击接收。

在运行服务器和客户端时，如果我查看终端中的 rails 后端，我会看到以下内容：

MessagesChannel 正在传输订阅确认 MessagesChannel 正在从 #Started GET "/api/v1/cable" for 127.0.0.1 at 2019-03-21 10:29:09 -0400 Started GET "/api/v1/cable/" [ WebSocket] for 127.0.0.1 at 2019-03-21 10:29:09 -0400 成功升级到 WebSocket (REQUEST_METHOD: GET, HTTP_CONNECTION: Upgrade, HTTP_UPGRADE: websocket) 无法执行来自 ({"command"=>"subscribe 的命令", "标识符"=>"{\"channel\":\"MessagesChannel\",\"game_id\":\"15\"}"}) [NoMethodError -[]' for nil:NilClass]: /Users/flatironschool/Development/code/Flatiron/mod5/project/deep_forest_api/app/channels/messages_channel.rb:3:in 订阅了未定义的方法' | /Users/flatironschool/.rvm/gems/ruby-2.6.1/gems/actioncable-5.2.2.1/lib/action_cable/channel/base.rb:179:in block in subscribe_to_channel' | /Users/flatironschool/.rvm/gems/ruby-2.6.1/gems/activesupport-5.2.2.1/lib/active_support/callbacks.rb:109:in block in run_callbacks' | /用户/flatironschool/。 wrap' | /Users/flatironschool/.rvm/gems/ruby-2.6.1/gems/actioncable-5.2.2.1/lib/action_cable/engine.rb:68:in '中的块（3个级别）

标签： javascriptruby-on-railsreactjswebsocketactioncable

解决方案

我从学校的 TCF 获得了帮助。

在我的消息频道中，我将其更改为：

  def subscribed
    @game = Game.find(params[:id][:game_id])
    stream_for @game
  end

所以，stream_for 而不是 stream_from。

此外，我还转而使用 npm 包 react-actioncable-provider。

我的客户端 javascript 在 React 中，看起来像这样：

import { ActionCable } from 'react-actioncable-provider';
import React, { Component, Fragment } from 'react';
import { CABLE, AUTH_HEADERS } from '../constants';
import { connect } from 'react-redux';
import Message from '../components/Message';

class Cable extends Component {

  render () {
    console.log("Cable.js")
    return (
      <Fragment>
        <ActionCable
          key={this.props.game_id}
          channel={{ channel: "MessagesChannel", game_id: this.props.game_id }}
          onReceived={(data) => console.log("handleReceived: ", data)}
        />
    </Fragment>
    )
  }
}

const mapStateToProps = state => {
  return { state }
}

const mapDispatchToProps = dispatch => {
  return {
    getMessages: data => dispatch({ type: "LOAD_MSGS", payload: data })
  }
}

export default connect(mapStateToProps, mapDispatchToProps)(Cable);

我现在能够接收来自 ActionCable 的响应。

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