如何在django模板中检查用户是否在线？

Question

在模板中,当我使用时

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

用户结果总是在线,即使他们刚刚退出.所以我想知道如何正确检查在线用户？

Answer 1

感谢这篇优秀的博文,稍作修改后,我想出了一个更好的解决方案,它使用了memcache,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:

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文件夹中添加此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)

settings.py中添加'userprofile.middleware.ActiveUserMiddleware',到MIDDLEWARE_CLASSES,也可以添加:

    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

并在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>

而已!

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'

Answer 2

正如文档所说：

尽管通常您会检查 request.user 上的 is_autheticated 属性以了解它是否已由 AuthenticationMiddleware（代表当前登录的用户）填充，但您应该知道该属性对于任何 User 实例都是 True 。

所以要检查用户是否在线，我会做这样的事情：

模型.py

class Profile(models.Model):
    user = models.OneToOneField(User, related_name='profile')           
    is_online = models.BooleanField(default=False)

视图.py

from django.contrib.auth.signals import user_logged_in, user_logged_out
from django.dispatch import receiver    

@receiver(user_logged_in)
def got_online(sender, user, request, **kwargs):    
    user.profile.is_online = True
    user.profile.save()

@receiver(user_logged_out)
def got_offline(sender, user, request, **kwargs):   
    user.profile.is_online = False
    user.profile.save()

然后在您的模板中，您将检查用户是否在线：

{% if user.profile.is_online %}
    Online
{% else %}
    Offline
{% endif %}

不要忘记将用户实例返回到您的模板以user.profile.is_online使其工作。