cookie
origin of the Cookie
We all know that HTTP protocol is stateless.
Stateless means each request is independent, its execution and results of previous requests and subsequent requests are not directly related, it is not limited by the foregoing request directly affect the response, it does not directly affect the back request response situation.
An interesting word to describe the life is only as strike, for the server, each request is new.
State data can be understood as a client and server created in a given session, and that no state to think that these data will not be retained. Session data generated is we need to be saved, that is to "hold." So Cookie is born under such a scenario.
What is Cookie
Cookie specifically referring to was a little information, it is the server sends out a bundle of keys stored on the browser's right, next time you access the server browser will automatically carry these key-value pairs, in order to extract useful information server .
Cookie principle
works cookie is: generated content from the server, the browser receives the request saved locally; when the browser visits, the browser will automatically bring the Cookie, so the server can be judged by the content of Cookie "who" was.
View Cookie
We use the Chrome browser, open the developer tools.
Django中操作Cookie
获取Cookie
request.COOKIES['key']
request.get_signed_cookie(key, default=RAISE_ERROR, salt='', max_age=None)
参数：
default: Default
salt: Salt encryption
max_age: background control expiration time
set cookies
REP = the HttpResponse (...)
REP = the render (Request, ...)
rep.set_cookie (Key, value, ...)
rep.set_signed_cookie (Key, value, = Salt 'encrypted salt', max_age = None, ...)
Parameters:
key, the key
value = '', the value
max_age = None, timeout
expires = None, timeout (IEs Expires The requires, IF IT SO SET has already been Not.)
path = '/', Cookie path in effect, / represents root path, special: cookie path may be the root page url to access any of the
domain name to take effect = None of the domain, Cookie
Secure = False, HTTPS transmission
httponly = False only http protocol transmission, JavaScript can not be acquired (not absolute, grasping the bottom package can be acquired may also be covered)
delete Cookie
DEF Zimbabwe Logout (Request):
REP = redirect ( "/ the Login /")
rep.delete_cookie ( "the user") # delete usercookie values previously set on the user's browser to
return REP
Cookie Edition Log parity
cookie Login
the Session
the Session of the origin of
Cookie solves the "hold" requirements to some extent, but due Cookie itself supports up to 4096 bytes, and Cookie itself is stored in the client may be intercepted or stolen, so you need to have a kinds of new things, it can support more bytes, and he saved on the server, there is high security. This is the Session.
The question is, based on the characteristics of the stateless HTTP protocol, the server does not know the visitor "who." Then the aforementioned Cookie will play the role of bridge.
We can give each client Cookie assigned a unique id, so that users access by Cookie, the server knows to the people "who." Then we id different based on Cookie's, private information stored on the server for some time, such as "account password" and so on.
In conclusion: Cookie up for the lack HTTP stateless, let the server know to the people "who"; however Cookie in the form of text stored locally, their security is poor; so we can identify the user through different Cookie, corresponding saving private information and text than 4096 bytes in the Session.
Further, the above-mentioned fact, Cookie and Session commonality things, not limited to the language and the frame.
Django related methods in Session
# 获取、设置、删除Session中数据
request.session['k1']
request.session.get('k1',None)
request.session['k1'] = 123
request.session.setdefault('k1',123) # 存在则不设置
del request.session['k1']
# 所有 键、值、键值对
request.session.keys()
request.session.values()
request.session.items()
request.session.iterkeys()
request.session.itervalues()
request.session.iteritems()
# 会话session的key
request.session.session_key
# 将所有Session失效日期小于当前日期的数据删除
request.session.clear_expired()
# 检查会话session的key在数据库中是否存在
request.session.exists("session_key")
# 删除当前会话的所有Session数据
request.session.delete()
# 删除当前的会话数据并删除会话的Cookie。
request.session.flush()
这用于确保前面的会话数据不可以再次被用户的浏览器访问
例如，django.contrib.auth.logout() 函数中就会调用它。
# 设置会话Session和Cookie的超时时间
request.session.set_expiry(value)
* 如果value是个整数，session会在些秒数后失效。
* 如果value是个datatime或timedelta，session就会在这个时间后失效。
* 如果value是0,用户关闭浏览器session就会失效。
* 如果value是None,session会依赖全局session失效策略。Session flow analysis
Session version login authentication
from functools import wraps
def check_login(func):
@wraps(func)
def inner(request, *args, **kwargs):
next_url = request.get_full_path()
if request.session.get("user"):
return func(request, *args, **kwargs)
else:
return redirect("/login/?next={}".format(next_url))
return inner
def login(request):
if request.method == "POST":
user = request.POST.get("user")
pwd = request.POST.get("pwd")
if user == "alex" and pwd == "alex1234":
# 设置session
request.session["user"] = user
# 获取跳到登陆页面之前的URL
next_url = request.GET.get("next")
# 如果有，就跳转回登陆之前的URL
if next_url:
return redirect(next_url)
# 否则默认跳转到index页面
else:
return redirect("/index/")
return render(request, "login.html")
@check_login
def logout(request):
# 删除所有当前请求相关的session
request.session.delete()
return redirect("/login/")
@check_login
def index(request):
current_user = request.session.get("user", None)
return render(request, "index.html", {"user": current_user})In Django Session configuration
Django default support Session, its interior offers five types of Session for developers to use.
1. 数据库Session
SESSION_ENGINE = 'django.contrib.sessions.backends.db' # 引擎（默认）
2. 缓存Session
SESSION_ENGINE = 'django.contrib.sessions.backends.cache' # 引擎
SESSION_CACHE_ALIAS = 'default' # 使用的缓存别名（默认内存缓存，也可以是memcache），此处别名依赖缓存的设置
3. 文件Session
SESSION_ENGINE = 'django.contrib.sessions.backends.file' # 引擎
SESSION_FILE_PATH = None # 缓存文件路径，如果为None，则使用tempfile模块获取一个临时地址tempfile.gettempdir()
4. 缓存+数据库
SESSION_ENGINE = 'django.contrib.sessions.backends.cached_db' # 引擎
5. 加密Cookie Session
SESSION_ENGINE = 'django.contrib.sessions.backends.signed_cookies' # 引擎
其他公用设置项：
SESSION_COOKIE_NAME ＝ "sessionid" # Session的cookie保存在浏览器上时的key，即：sessionid＝随机字符串（默认）
SESSION_COOKIE_PATH ＝ "/" # Session的cookie保存的路径（默认）
SESSION_COOKIE_DOMAIN = None # Session的cookie保存的域名（默认）
SESSION_COOKIE_SECURE = False # 是否Https传输cookie（默认）
SESSION_COOKIE_HTTPONLY = True # 是否Session的cookie只支持http传输（默认）
SESSION_COOKIE_AGE = 1209600 # Session的cookie失效日期（2周）（默认）
SESSION_EXPIRE_AT_BROWSER_CLOSE = False # 是否关闭浏览器使得Session过期（默认）
SESSION_SAVE_EVERY_REQUEST = False # 是否每次请求都保存Session，默认修改之后才保存（默认）CBV Canada decorator related
CBV realized login view
class LoginView(View):
def get(self, request):
"""
处理GET请求
"""
return render(request, 'login.html')
def post(self, request):
"""
处理POST请求
"""
user = request.POST.get('user')
pwd = request.POST.get('pwd')
if user == 'alex' and pwd == "alex1234":
next_url = request.GET.get("next")
# 生成随机字符串
# 写浏览器cookie -> session_id: 随机字符串
# 写到服务端session：
# {
# "随机字符串": {'user':'alex'}
# }
request.session['user'] = user
if next_url:
return redirect(next_url)
else:
return redirect('/index/')
return render(request, 'login.html')To use our above check_login decorator in CBV view, there are three ways:
from django.utils.decorators import method_decorator
- Get or post added to the view method of CBV
from django.utils.decorators import method_decorator
class HomeView(View):
def dispatch(self, request, *args, **kwargs):
return super(HomeView, self).dispatch(request, *args, **kwargs)
def get(self, request):
return render(request, "home.html")
@method_decorator(check_login)
def post(self, request):
print("Home View POST method...")
return redirect("/index/")- Added to the dispatch method
from django.utils.decorators import method_decorator
class HomeView(View):
@method_decorator(check_login)
def dispatch(self, request, *args, **kwargs):
return super(HomeView, self).dispatch(request, *args, **kwargs)
def get(self, request):
return render(request, "home.html")
def post(self, request):
print("Home View POST method...")
return redirect("/index/")
因为CBV中首先执行的就是dispatch方法，所以这么写相当于给get和post方法都加上了登录校验。- Applied directly to the view class, but must pass the name key parameters method_decorator
如果get方法和post方法都需要登录校验的话就写两个装饰器。
from django.utils.decorators import method_decorator
@method_decorator(check_login, name="get")
@method_decorator(check_login, name="post")
class HomeView(View):
def dispatch(self, request, *args, **kwargs):
return super(HomeView, self).dispatch(request, *args, **kwargs)
def get(self, request):
return render(request, "home.html")
def post(self, request):
print("Home View POST method...")
return redirect("/index/")
Supplementary
CSRF Token related decoration applied only in CBV dispatch method, or add and name parameter specifies the dispatch method on the view class.
Remarks:
csrf_protect, forced to current function CSRF prevention function, even if there is no intermediate settings in global settings.
csrf_exempt, it cancels the current function CSRF prevention function, even if the global settings set in the middleware.
from django.views.decorators.csrf import csrf_exempt, csrf_protect
from django.utils.decorators import method_decorator
class HomeView(View):
@method_decorator(csrf_exempt)
def dispatch(self, request, *args, **kwargs):
return super(HomeView, self).dispatch(request, *args, **kwargs)
def get(self, request):
return render(request, "home.html")
def post(self, request):
print("Home View POST method...")
return redirect("/index/")
from django.views.decorators.csrf import csrf_exempt, csrf_protect
from django.utils.decorators import method_decorator
@method_decorator(csrf_exempt, name='dispatch')
class HomeView(View):
def dispatch(self, request, *args, **kwargs):
return super(HomeView, self).dispatch(request, *args, **kwargs)
def get(self, request):
return render(request, "home.html")
def post(self, request):
print("Home View POST method...")
return redirect("/index/")Paging
When there is a lot of data in the database, we usually do pagination display in the front page.
Paging data can be achieved in the front page, you can also implement paging in the back end.
Back-end implementation of the principle of paging is a time request a page of data.
Ready to work
We use a batch script to create some test data (Save the following code to bulk_create.py file into the root directory of your Django project, can be directly executed.):
import os
if __name__ == "__main__":
os.environ.setdefault("DJANGO_SETTINGS_MODULE", "about_orm.settings")
import django
django.setup()
from app01 import models
bulk_obj = (models.Publisher(name='沙河第{}出版社'.format(i)) for i in range(300))
models.Publisher.objects.bulk_create(bulk_obj)Custom Paging
def publisher_list(request):
# 从URL中取当前访问的页码数
try:
current_page = int(request.GET.get('page'))
except Exception as e:
# 取不到或者页码数不是数字都默认展示第1页
current_page = 1
# 总数据量
total_count = models.Publisher.objects.count()
# 定义每页显示多少条数据
per_page = 10
# 计算出总页码数
total_page, more = divmod(total_count, per_page)
if more:
total_page += 1
# 定义页面上最多显示多少页码(为了左右对称，一般设为奇数)
max_show = 11
half_show = max_show // 2
# 计算一下页面显示的页码范围
if total_page <= max_show: # 总页码数小于最大显示页码数
page_start = 1
page_end = total_page
elif current_page + half_show >= total_page: # 右边越界
page_end = total_page
page_start = total_page - max_show
elif current_page - half_show <= 1: # 左边越界
page_start = 1
page_end = max_show
else: # 正常页码区间
page_start = current_page - half_show
page_end = current_page + half_show
# 数据索引起始位置
data_start = (current_page-1) * per_page
data_end = current_page * per_page
publisher_list = models.Publisher.objects.all()[data_start:data_end]
# 生成页面上显示的页码
page_html_list = []
page_html_list.append('<nav aria-label="Page navigation"><ul class="pagination">')
# 加首页
first_li = '<li><a href="/publisher_list/?page=1">首页</a></li>'
page_html_list.append(first_li)
# 加上一页
if current_page == 1:
prev_li = '<li><a href="#"><span aria-hidden="true">«</span></a></li>'
else:
prev_li = '<li><a href="/publisher_list/?page={}"><span aria-hidden="true">«</span></a></li>'.format(current_page - 1)
page_html_list.append(prev_li)
for i in range(page_start, page_end + 1):
if i == current_page:
li_tag = '<li class="active"><a href="/publisher_list/?page={0}">{0}</a></li>'.format(i)
else:
li_tag = '<li><a href="/publisher_list/?page={0}">{0}</a></li>'.format(i)
page_html_list.append(li_tag)
# 加下一页
if current_page == total_page:
next_li = '<li><a href="#"><span aria-hidden="true">»</span></a></li>'
else:
next_li = '<li><a href="/publisher_list/?page={}"><span aria-hidden="true">»</span></a></li>'.format(current_page + 1)
page_html_list.append(next_li)
# 加尾页
page_end_li = '<li><a href="/publisher_list/?page={}">尾页</a></li>'.format(total_page)
page_html_list.append(page_end_li)
page_html_list.append('</ul></nav>')
page_html = "".join(page_html_list)
return render(request, "publisher_list.html", {"publisher_list": publisher_list, "page_html": page_html})class Pagination(object):
"""自定义分页（Bootstrap版）"""
def __init__(self, current_page, total_count, base_url, per_page=10, max_show=11):
"""
:param current_page: 当前请求的页码
:param total_count: 总数据量
:param base_url: 请求的URL
:param per_page: 每页显示的数据量，默认值为10
:param max_show: 页面上最多显示多少个页码，默认值为11
"""
try:
self.current_page = int(current_page)
except Exception as e:
# 取不到或者页码数不是数字都默认展示第1页
self.current_page = 1
# 定义每页显示多少条数据
self.per_page = per_page
# 计算出总页码数
total_page, more = divmod(total_count, per_page)
if more:
total_page += 1
self.total_page = total_page
# 定义页面上最多显示多少页码(为了左右对称，一般设为奇数)
self.max_show = max_show
self.half_show = max_show // 2
self.base_url = base_url
@property
def start(self):
return (self.current_page-1) * self.per_page
@property
def end(self):
return self.current_page * self.per_page
def page_html(self):
# 计算一下页面显示的页码范围
if self.total_page <= self.max_show: # 总页码数小于最大显示页码数
page_start = 1
page_end = self.total_page
elif self.current_page + self.half_show >= self.total_page: # 右边越界
page_end = self.total_page
page_start = self.total_page - self.max_show
elif self.current_page - self.half_show <= 1: # 左边越界
page_start = 1
page_end = self.max_show
else: # 正常页码区间
page_start = self.current_page - self.half_show
page_end = self.current_page + self.half_show
# 生成页面上显示的页码
page_html_list = []
page_html_list.append('<nav aria-label="Page navigation"><ul class="pagination">')
# 加首页
first_li = '<li><a href="{}?page=1">首页</a></li>'.format(self.base_url)
page_html_list.append(first_li)
# 加上一页
if self.current_page == 1:
prev_li = '<li><a href="#"><span aria-hidden="true">«</span></a></li>'
else:
prev_li = '<li><a href="{}?page={}"><span aria-hidden="true">«</span></a></li>'.format(
self.base_url, self.current_page - 1)
page_html_list.append(prev_li)
for i in range(page_start, page_end + 1):
if i == self.current_page:
li_tag = '<li class="active"><a href="{0}?page={1}">{1}</a></li>'.format(self.base_url, i)
else:
li_tag = '<li><a href="{0}?page={1}">{1}</a></li>'.format(self.base_url, i)
page_html_list.append(li_tag)
# 加下一页
if self.current_page == self.total_page:
next_li = '<li><a href="#"><span aria-hidden="true">»</span></a></li>'
else:
next_li = '<li><a href="{}?page={}"><span aria-hidden="true">»</span></a></li>'.format(
self.base_url, self.current_page + 1)
page_html_list.append(next_li)
# 加尾页
page_end_li = '<li><a href="{}?page={}">尾页</a></li>'.format(self.base_url, self.total_page)
page_html_list.append(page_end_li)
page_html_list.append('</ul></nav>')
return "".join(page_html_list)def publisher_list(request):
# 从URL中取当前访问的页码数
current_page = int(request.GET.get('page'))
# 比len(models.Publisher.objects.all())更高效
total_count = models.Publisher.objects.count()
page_obj = Pagination(current_page, total_count, request.path_info)
data = models.Publisher.objects.all()[page_obj.start:page_obj.end]
page_html = page_obj.page_html()
return render(request, "publisher_list.html", {"publisher_list": data, "page_html": page_html})Django built pagination
from django.shortcuts import render
from django.core.paginator import Paginator, EmptyPage, PageNotAnInteger
L = []
for i in range(999):
L.append(i)
def index(request):
current_page = request.GET.get('p')
paginator = Paginator(L, 10)
# per_page: 每页显示条目数量
# count: 数据总个数
# num_pages:总页数
# page_range:总页数的索引范围，如: (1,10),(1,200)
# page: page对象
try:
posts = paginator.page(current_page)
# has_next 是否有下一页
# next_page_number 下一页页码
# has_previous 是否有上一页
# previous_page_number 上一页页码
# object_list 分页之后的数据列表
# number 当前页
# paginator paginator对象
except PageNotAnInteger:
posts = paginator.page(1)
except EmptyPage:
posts = paginator.page(paginator.num_pages)
return render(request, 'index.html', {'posts': posts})
<!DOCTYPE html>
<html>
<head lang="en">
<meta charset="UTF-8">
<title></title>
</head>
<body>
<ul>
{% for item in posts %}
<li>{{ item }}</li>
{% endfor %}
</ul>
<div class="pagination">
<span class="step-links">
{% if posts.has_previous %}
<a href="?p={{ posts.previous_page_number }}">Previous</a>
{% endif %}
<span class="current">
Page {{ posts.number }} of {{ posts.paginator.num_pages }}.
</span>
{% if posts.has_next %}
<a href="?p={{ posts.next_page_number }}">Next</a>
{% endif %}
</span>
</div>
</body>
</html>