这里有新鲜出炉的Django 入门教程,程序狗速度看过来!
Django是一个开放源代码的Web应用框架,由Python写成。采用了MVC的软件设计模式,即模型M,视图V和控制器C。它最初是被开发来用于管理劳伦斯出版集团旗下的一些以新闻内容为主的网站的,即是CMS(内容管理系统)软件。并于2005年7月在BSD许可证下发布。这套框架是以比利时的吉普赛爵士吉他手Django Reinhardt来命名的。
周末小闲在家研究了下django的 cookie 和 session,所以下面这篇文章主要给大家深入地介绍了关于Django中Session与Cookie的相关资料,文中通过示例代码介绍的非常详细,需要的朋友们下面跟着小编来一起看看吧。
前言
Cookie和Session相信对大家来说并不陌生,简单来说,Cookie和Session都是为了记录用户相关信息的方式,最大的区别就是Cookie在客户端记录而Session在服务端记录内容。
那么Cookie和Session之间的联系是怎么建立的呢?换言之,当服务器接收到一个请求时候,根据什么来判断读取哪个Session的呢?
对于Django默认情况来说,当用户登录后就可以发现Cookie里有一个sessionid的字段,根据这个key就可以取得在服务器端记录的详细内容。如果将这个字段删除,刷新页面就会发现变成未登录状态了。
对于Session的处理主要在源码django/contrib/sessions/middleware.py中,如下所示:
- import time
- from importlib import import_module
- from django.conf import settings
- from django.contrib.sessions.backends.base import UpdateError
- from django.core.exceptions import SuspiciousOperation
- from django.utils.cache import patch_vary_headers
- from django.utils.deprecation import MiddlewareMixin
- from django.utils.http import cookie_date
- class SessionMiddleware(MiddlewareMixin):
- def __init__(self, get_response=None):
- self.get_response = get_response
- engine = import_module(settings.SESSION_ENGINE)
- self.SessionStore = engine.SessionStore
- def process_request(self, request):
- session_key = request.COOKIES.get(settings.SESSION_COOKIE_NAME)
- request.session = self.SessionStore(session_key)
- def process_response(self, request, response):
- """
- If request.session was modified, or if the configuration is to save the
- session every time, save the changes and set a session cookie or delete
- the session cookie if the session has been emptied.
- """
- try:
- accessed = request.session.accessed
- modified = request.session.modified
- empty = request.session.is_empty()
- except AttributeError:
- pass
- else:
- # First check if we need to delete this cookie.
- # The session should be deleted only if the session is entirely empty
- if settings.SESSION_COOKIE_NAME in request.COOKIES and empty:
- response.delete_cookie(
- settings.SESSION_COOKIE_NAME,
- path=settings.SESSION_COOKIE_PATH,
- domain=settings.SESSION_COOKIE_DOMAIN,
- )
- else:
- if accessed:
- patch_vary_headers(response, ('Cookie',))
- if (modified or settings.SESSION_SAVE_EVERY_REQUEST) and not empty:
- if request.session.get_expire_at_browser_close():
- max_age = None
- expires = None
- else:
- max_age = request.session.get_expiry_age()
- expires_time = time.time() + max_age
- expires = cookie_date(expires_time)
- # Save the session data and refresh the client cookie.
- # Skip session save for 500 responses, refs #3881.
- if response.status_code != 500:
- try:
- request.session.save()
- except UpdateError:
- raise SuspiciousOperation(
- "The request's session was deleted before the "
- "request completed. The user may have logged "
- "out in a concurrent request, for example."
- )
- response.set_cookie(
- settings.SESSION_COOKIE_NAME,
- request.session.session_key, max_age=max_age,
- expires=expires, domain=settings.SESSION_COOKIE_DOMAIN,
- path=settings.SESSION_COOKIE_PATH,
- secure=settings.SESSION_COOKIE_SECURE or None,
- httponly=settings.SESSION_COOKIE_HTTPONLY or None,
- )
- return response
当接收到一个请求时候,先在Cookie里取出key,然后根据key创建Session对象,在response时候判断是否要删除或者修改sessionid。
也就是说,Django中如果客户把浏览器Cookie禁用后,用户相关的功能就全都失效了,因为服务端根本没法知道当前用户是谁。
对于这种情况,关键点就是如何把sessionid不使用Cookie传递给客户端,常见的比如放在URL中,也就是URL重写技术。想实现这点可以自己写Middleware。不过django并不建议这么做:
The Django sessions framework is entirely, and solely, cookie-based. It does not fall back to putting session IDs in URLs as a last resort, as PHP does. This is an intentional design decision. Not only does that behavior make URLs ugly, it makes your site vulnerable to session-ID theft via the “Referer” header.
总结
以上就是这篇文章的全部内容了,希望本文的内容对大家的学习或者工作能带来一定的帮助,如果有疑问大家可以留言交流,谢谢大家对PHPERZ的支持
来源: http://www.phperz.com/article/17/1026/351101.html