django-channels实际应用

django实现websocket实时数据推送。

应用场景

• 群组/单对单语音聊天
• 页面数据实时推送（后端主导）

技术

django + channels

django >=2

channels官方

wsgi

Web服务器网关接口（Python Web Server Gateway Interface，缩写为WSGI）是为Python语言定义的Web服务器和Web应用程序或框架之间的一种简单而通用的接口。自从WSGI被开发出来以后，许多其它语言中也出现了类似接口

asgi

ASGI(Asynchronous Server Gateway Interface, 异步服务器网关接口) 是WSGI的传人，为了规范支持异步的Python网络服务器，框架和应用之间的通信而定制

http使用wsgi而websocket使用asgi

项目目录架构

- project
	- project
		- settings.py
		- wsgi.py
		- asgi.py
		- urls.py
	- ws
		- routings.py
		- consumers.py

配置

django - settings.py

注意： redis版本必须依赖>=5x

redis_url = f'redis://default:{redis_password}@{redis_host}:{redis_port}'
ASGI_APPLICATION = 'project.asgi.application'
CHANNEL_LAYERS = {
    'default': {
        'BACKEND': 'channels_redis.core.RedisChannelLayer',
        'CONFIG': {
            'hosts': [f'{redis_url}/0'],
          	# django SECRET_KEY
            'symmetric_encryption_keys': [SECRET_KEY]
        }
    }
}

asgi

import os
from django.core.asgi import get_asgi_application
from channels.routing import ProtocolTypeRouter, URLRouter

os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'project.settings')
django_asgi_app = get_asgi_application()

# 部署时 防止找不到包
import ws.routings

application = ProtocolTypeRouter(
    {
        'http': django_asgi_app,
        'websocket': URLRouter(ws.routings.websocket_urlpatterns)
    }
)

routings

类似Django的urls

from django.urls import re_path
from ws import consumers

websocket_urlpatterns = [
    # 心跳
    re_path(r'^heartbeat/(?P<room_name>\w+)/$', consumers.BaseConsumer.as_asgi()),
]

视图

concumers,py 类似django视图

使用异步消费者

from channels.generic.websocket import AsyncWebsocketConsumer


class BaseConsumer(AsyncWebsocketConsumer):

    async def connect(self):
        self.group_name = self.scope['url_route']['kwargs']['room_name']
        self.room_group_name = 'chat_%s' % self.group_name
        await self.channel_layer.group_add(
            self.room_group_name,
            self.channel_name
        )
        await self.accept()

        # 连接成功消息
        await self.channel_layer.group_send(
            self.room_group_name,
            {
                'type': 'chat_data',
                'data': {
                    'msg': 'heartbeat',
                    'code': 200,
                    'data': []
                }
            }
        )

    async def disconnect(self, close_code):
        # Leave room group
        await self.channel_layer.group_discard(
            self.room_group_name,
            self.channel_name
        )

    # Receive message from WebSocket
    async def receive(self, text_data):
      	# 测试收发，根据情况修改
        text_data_json = json.loads(text_data)
        message = text_data_json['message']

        # Send message to room group
        await self.channel_layer.group_send(
            self.room_group_name,
            {
                'type': 'chat_data',
                'data': {'message': message}
            }
        )

    # Receive message from room group
    async def chat_data(self, event):
        # Send message to WebSocket
        await self.send(text_data=json.dumps(event['data']))

    async def msg_send(self, data, msg='success', code=200, ):
        """推送数据"""
        await self.channel_layer.group_send(
            self.room_group_name,
            {
                'type': 'chat_data',
                'data': {
                    'msg': msg,
                    'code': code,
                    'data': data
                }
            }
        )

如果使用django的queryset

  from channels.db import database_sync_to_async
  
  await database_sync_to_async(self.get_data)(text_data_json)

如果不在consumers逻辑中使用websocket

class SendMessage:
    """服务端 --> 客户端 推送"""

    def __init__(self, room_group_name):
        self.channel_layer = get_channel_layer()
        self.room_group_name = 'chat_%s' % room_group_name

    async def send(self, val: dict):
        """
        chat_type: chat.chat_name
        """
        chat_type = val.pop('chat_type')
        await self.channel_layer.group_send(
            self.room_group_name,
            {
                'type': chat_type,
                'data': {
                    'data': val,
                    'msg': 'success',
                    'code': 200
                } if not val.get('code') else val
            }
        )

部署

部署使用daphne

daphne -b 0.0.0.0 -p 8010 --proxy-headers project.asgi:application