Django Channels Websockets 立即连接和断开连接

Posted 2023-02-16

【中文标题】Django Channels Websockets 立即连接和断开连接

【英文标题】：Django Channels Websockets Connecting and Disconnecting right away

【发布时间】：2017-03-06 00:45:11

【问题描述】：

首先是一些背景知识，我正在学习本教程： https://blog.heroku.com/in_deep_with_django_channels_the_future_of_real_time_apps_in_django 在 Windows 64 位上使用 Redis 的 Vagrant 发行版从这里： https://github.com/ServiceStack/redis-windows 使用 Python 3.4 和 Django 1.10

我能够很好地克隆、构建和运行项目。问题是，当我通过浏览器访问 django 视图时，它可以正常加载聊天，但是当我在控制台中发送消息时，它说 websocket 连接然后几乎立即断开连接并且消息不发送。如果我手动将数据输入数据库，那么当我第一次加载视图时会显示消息，但由于某种原因，javascript 应用程序无法保持 websocket 打开以发送消息以进行广播。下面是相关代码：

consumers.py

import re
import json
import logging
from channels import Group
from channels.sessions import channel_session
from .models import Room

log = logging.getLogger(__name__)

@channel_session
def ws_connect(message):
    # Extract the room from the message. This expects message.path to be of the
    # form /chat/label/, and finds a Room if the message path is applicable,
    # and if the Room exists. Otherwise, bails (meaning this is a some othersort
    # of websocket). So, this is effectively a version of _get_object_or_404.
    try:
        prefix, label = message['path'].strip('/').split('/')
        if prefix != 'chat':
            log.debug('invalid ws path=%s', message['path'])
            return
        room = Room.objects.get(label=label)
    except ValueError:
        log.debug('invalid ws path=%s', message['path'])
        return
    except Room.DoesNotExist:
        log.debug('ws room does not exist label=%s', label)
        return

    log.debug('chat connect room=%s client=%s:%s', 
        room.label, message['client'][0], message['client'][1])

    # Need to be explicit about the channel layer so that testability works
    # This may be a FIXME?
    Group('chat-'+label, channel_layer=message.channel_layer).add(message.reply_channel)

    message.channel_session['room'] = room.label


@channel_session
def ws_receive(message):
    # Look up the room from the channel session, bailing if it doesn't exist
    try:
        label = message.channel_session['room']
        room = Room.objects.get(label=label)
    except KeyError:
        log.debug('no room in channel_session')
        print('no room in channel_session')
        return
    except Room.DoesNotExist:
        log.debug('recieved message, buy room does not exist label=%s', label)
        print('recieved message, buy room does not exist label=%s', label)
        return

    # Parse out a chat message from the content text, bailing if it doesn't
    # conform to the expected message format.
    try:
        data = json.loads(message['text'])
    except ValueError:
        log.debug("ws message isn't json text=%s", text)
        print("ws message isn't json text=%s", text)
        return

    if set(data.keys()) != set(('handle', 'message')):
        log.debug("ws message unexpected format data=%s", data)
        print("ws message unexpected format data=%s", data)
        return

    if data:
        log.debug('chat message room=%s handle=%s message=%s', 
            room.label, data['handle'], data['message'])
        print('chat message room=%s handle=%s message=%s', 
            room.label, data['handle'], data['message'])
        m = room.messages.create(**data)

        # See above for the note about Group
        Group('chat-'+label, channel_layer=message.channel_layer).send('text': json.dumps(m.as_dict()))


@channel_session
def ws_disconnect(message):
    try:
        label = message.channel_session['room']
        room = Room.objects.get(label=label)
        Group('chat-'+label, channel_layer=message.channel_layer).discard(message.reply_channel)
    except (KeyError, Room.DoesNotExist):
        pass

聊天.js

$(function() 
    // When we're using HTTPS, use WSS too.
    var ws_scheme = window.location.protocol == "https:" ? "wss" : "ws";
    var chatsock = new WebSocket(ws_scheme + '://' + window.location.host + "/chat" + window.location.pathname);

    chatsock.onmessage = function(message) 
        var data = JSON.parse(message.data);
        var chat = $("#chat")
        var ele = $('<tr></tr>')

        ele.append(
            $("<td></td>").text(data.timestamp)
        )
        ele.append(
            $("<td></td>").text(data.handle)
        )
        ele.append(
            $("<td></td>").text(data.message)
        )

        chat.append(ele)
    ;

    $("#chatform").on("submit", function(event) 
        var message = 
            handle: $('#handle').val(),
            message: $('#message').val(),
        
        chatsock.send(JSON.stringify(message));
        $("#message").val('').focus();
        return false;
    );
);

views.py

import random
import string
from django.db import transaction
from django.shortcuts import render, redirect
from haikunator import Haikunator
from .models import Room

def about(request):
    return render(request, "chat/about.html")

def new_room(request):
    """
    Randomly create a new room, and redirect to it.
    """
    haikunator = Haikunator()
    new_room = None
    while not new_room:
        with transaction.atomic():
            label = haikunator.haikunate()
            if Room.objects.filter(label=label).exists():
                continue
            new_room = Room.objects.create(label=label)
    return redirect(chat_room, label=label)

def chat_room(request, label):
    """
    Room view - show the room, with latest messages.
    The template for this view has the WebSocket business to send and stream
    messages, so see the template for where the magic happens.
    """
    # If the room with the given label doesn't exist, automatically create it
    # upon first visit (a la etherpad).
    room, created = Room.objects.get_or_create(label=label)

    # We want to show the last 50 messages, ordered most-recent-last
    messages = reversed(room.messages.order_by('-timestamp')[:50])

    return render(request, "chat/room.html", 
        'room': room,
        'messages': messages,
    )

models.py

from __future__ import unicode_literals

from django.db import models
from django.utils import timezone

class Room(models.Model):
    name = models.TextField()
    label = models.SlugField(unique=True)

    def __unicode__(self):
        return self.label

class Message(models.Model):
    room = models.ForeignKey(Room, related_name='messages')
    handle = models.TextField()
    message = models.TextField()
    timestamp = models.DateTimeField(default=timezone.now, db_index=True)

    def __unicode__(self):
        return '[timestamp] handle: message'.format(**self.as_dict())

    # @property
    # def formatted_timestamp(self):
    #     return self.timestamp.strftime('%b %-d %-I:%M %p')

    def as_dict(self):
        return 'handle': self.handle, 'message': self.message, 'timestamp': self.formatted_timestamp

我一直在使用 javascript 来查看是否可以让 websockets 保持打开状态，我也尝试过 Simple Websocket Client https://chrome.google.com/webstore/detail/simple-websocket-client/pfdhoblngboilpfeibdedpjgfnlcodoo?hl=en

这和那些让我相信它与 python 代码有关的事情是一样的吗？

编辑 1： 这是javascript应用程序的开发者控制台 http://imgur.com/AyIGB0z

这是运行 daphne 后的控制台输出 http://imgur.com/p2yyZiJ

【参考方案1】：

渠道变化很快，因此您的消费者只发生了一些细微的变化。注意message.reply_channel.send('accept': True)的底线

consumers.py

@channel_session
def ws_connect(message):
    prefix, label = message['path'].strip('/').split('/')
    room = Room.objects.get(label=label)
    Group('chat-' + label).add(message.reply_channel)
    message.channel_session['room'] = room.label
    message.reply_channel.send('accept': True)

@channel_session
def ws_receive(message):
    label = message.channel_session['room']
    room = Room.objects.get(label=label)
    data = json.loads(message['text'])
    m = room.messages.create(handle=data['handle'], message=data['message'])
    Group('chat-'+label).send('text': json.dumps(m.as_dict()))

@channel_session
def ws_disconnect(message):
    label = message.channel_session['room']
    Group('chat-'+label).discard(message.reply_channel)

另外，当您使用Haikunator 时，您需要定义它的参数。如：

haikunator = Haikunator(
    adjectives=['custom', 'adjectives'],
    nouns=['custom', 'nouns'],
    seed='random seed'
)

haikunator.haikunate(
  delimiter='-',
  token_length=4,
  token_hex=False,
  token_chars='0123456789'
)

希望这会有所帮助。

【讨论】：

即使添加了“接受”消息，Chrome 仍然无法正常工作。 Firefox 和 Safari 也可以使用它。