django - 如何在django模板中检查用户是否在线？

Question

在模板中，当我使用

{% if topic.creator.is_authenticated %}
Online
{% else %}
Offline
{% endif %}

结果证明，用户始终在线，即使他们已退出一段时间。所以我想知道如何正确检查在线用户？

Answer 1

‌谢谢this优秀的博客文章，稍作修改，我想出了一个更好的解决方案，它使用内存缓存，因此每个请求的延迟更少:

在models.py中添加:

from django.core.cache import cache 
import datetime
from myproject import settings

并将这些方法添加到 userprofile 类中:

def last_seen(self):
    return cache.get('seen_%s' % self.user.username)

def online(self):
    if self.last_seen():
        now = datetime.datetime.now()
        if now > self.last_seen() + datetime.timedelta(
                     seconds=settings.USER_ONLINE_TIMEOUT):
            return False
        else:
            return True
    else:
        return False 

在 userprofile 文件夹中添加这个 middleware.py

import datetime
from django.core.cache import cache
from django.conf import settings

class ActiveUserMiddleware:

    def process_request(self, request):
        current_user = request.user
        if request.user.is_authenticated():
            now = datetime.datetime.now()
            cache.set('seen_%s' % (current_user.username), now, 
                           settings.USER_LASTSEEN_TIMEOUT)

在 settings.py 中添加 'userprofile.middleware.ActiveUserMiddleware',至 MIDDLEWARE_CLASSES并添加:

    CACHES = {
        'default': {
            'BACKEND': 'django.core.cache.backends.memcached.MemcachedCache',
            'LOCATION': '127.0.0.1:11211',              
        }
    }

# Number of seconds of inactivity before a user is marked offline
USER_ONLINE_TIMEOUT = 300

# Number of seconds that we will keep track of inactive users for before 
# their last seen is removed from the cache
USER_LASTSEEN_TIMEOUT = 60 * 60 * 24 * 7

在 profile.html 中:

 <table>
   <tr><th>Last Seen</th><td>{% if profile.last_seen %}{{ profile.last_seen|timesince }}{% else %}awhile{% endif %} ago</td></tr>
   <tr><th>Online</th><td>{{ profile.online }}</td></tr>
 </table>

就是这样!

要在控制台中测试缓存，以确保 memcache 正常工作:

$memcached -vv
$ python manage.py shell
>>> from django.core.cache import cache
>>> cache.set("foo", "bar")
>>> cache.get("foo")
'bar'
>>> cache.set("foo", "zaq")
>>> cache.get("foo")
'zaq'