Django：使用基于Cookie的会话存储时会话缓存未更新 [英] Django: Session Cache not updated when using Cookie Based Session Storage

问题描述

我想使用Django Session来缓存一些数据。我在我的web应用程序没有数据库，所以，我使用基于cookie的存储机制。我只能第一次成功地保存数据在会话中。从此，如果我尝试更新会话缓存，它不工作。这是我发现了：

  prior_states = request.session.get（workflow_id，[]）
 print prior_state>>>，则before_states 
 if state_id in prior_states：
 request.session.update（{workflow_id：prior_states [：prior_states.index（state_id）+ 1]}）
 else：
 prior_states.append（state_id）
 request.session.update（{workflow_id：prior_states}）
  

测试代码

 code>＃first request：
 print request.session.get（1） - >无
 request.session [1] = [101]  - > works 
 print request.session.get（1） - > [101] 
＃第二个请求：
 print request.session.get（1） - > [101] 
 request.session [1] = [101，102]  - > works 
 print request.session.get（1） - > [101,102] 
 
＃第三个请求：
 print request.session.get（1） - > [101]  - >不能跟随为什么？ 
  

提前感谢！

方案

根据Django文档：

https://docs.djangoproject.com/en/1.6/topics/http/sessions/#when-sessions-are-saved

默认情况下，Django仅在会话
被修改时保存到会话数据库 - 字典值已分配或删除

  request.session.modified = True 
  

要更改此默认行为，请将SESSION_SAVE_EVERY_REQUEST设置设置为True。设置为True时，Django会在每次请求时将会话保存到数据库。

请注意，会话cookie仅在创建或修改会话时发送。如果SESSION_SAVE_EVERY_REQUEST为True，则会在每个请求中发送会话Cookie。

同样，会话cookie的expires部分在每次发送会话cookie时更新。 / p>

I am trying to use Django Session to cache some data. I don't have a database in my web app so, I am using the cookie-based storage mechanism. I am able to successfully save the data in the session only for the first time. Henceforth, if I try to update the session cache it doesn't work. Here is what I had found:

prior_states = request.session.get(workflow_id, [])
print "prior_state >>> ", prior_states
if state_id in prior_states:
    request.session.update({workflow_id: prior_states[:prior_states.index(state_id) + 1]})
else:
     prior_states.append(state_id)
     request.session.update({workflow_id : prior_states})

Test Code

#1st request:
print request.session.get(1) --> None
request.session[1] = [101] --> works
print request.session.get(1) --> [101]
#2nd request:
print request.session.get(1) --> [101]
request.session[1] = [101, 102] --> works
print request.session.get(1) --> [101,102]

#3rd request:
print request.session.get(1) --> [101] --> Can't follow why?

Thanks in advance!

解决方案

According to the Django Documentation:

https://docs.djangoproject.com/en/1.6/topics/http/sessions/#when-sessions-are-saved

By default, Django only saves to the session database when the session has been modified – that is if any of its dictionary values have been assigned or deleted

request.session.modified = True

To change this default behavior, set the SESSION_SAVE_EVERY_REQUEST setting to True. When set to True, Django will save the session to the database on every single request.

Note that the session cookie is only sent when a session has been created or modified. If SESSION_SAVE_EVERY_REQUEST is True, the session cookie will be sent on every request.

Similarly, the expires part of a session cookie is updated each time the session cookie is sent.

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