day05 django知识点
今日概要:
- 中间件 【使用】【源码】
- cookie 【使用】【源码 - Django底层请求本质】
- session【使用】【源码 - 数据库+请求周期+中间件】
1.中间件
1.1 使用
- 编写类,在类型定义:process_request、process_view、process_response
- 中间件注册,在settings中的配置。
1.1.1 正常
1.编写类
可以写在任意的目录:自定义的类、继承一个类**(推荐)**
python
from django.utils.deprecation import MiddlewareMixin
class KeLaMiddleware(MiddlewareMixin):
def process_request(self, request):
# request是请求相关所有的数据
pass
def process_view(self, request, view, *args, **kwargs):
# request是请求相关所有的数据; view是试图函数; 路由参数*args, **kwargs
pass
def process_response(self, request, response):
# request是请求相关所有的数据
# response是试图函数返回的那个对象(封装了要返回到用户浏览器的所有数据)
return response
2.注册
python
MIDDLEWARE = [
'django.middleware.security.SecurityMiddleware',
'django.contrib.sessions.middleware.SessionMiddleware',
'django.middleware.common.CommonMiddleware',
'django.middleware.csrf.CsrfViewMiddleware',
'django.contrib.auth.middleware.AuthenticationMiddleware',
'django.contrib.messages.middleware.MessageMiddleware',
'django.middleware.clickjacking.XFrameOptionsMiddleware',
"utils.md.KeLaMiddleware"
]
# 动态导入 + 反射
3.测试
python
from django.utils.deprecation import MiddlewareMixin
class KeLaMiddleware(MiddlewareMixin):
def process_request(self, request):
print("KeLa.process_request")
def process_view(self, request, view, *args, **kwargs):
print("KeLa.process_view",view, *args, **kwargs)
def process_response(self, request, response):
print("KeLa.process_response")
return response
python
from django.contrib import admin
from django.urls import path
from django.shortcuts import HttpResponse
def x1(request):
print("视图.x1")
return HttpResponse("x1")
def x2(request, v1):
print("视图.x2", v1)
return HttpResponse("x2")
urlpatterns = [
path('admin/', admin.site.urls),
path('x1/', x1),
path('x2/<int:v1>/', x2),
]
python
MIDDLEWARE = [
'django.middleware.security.SecurityMiddleware',
'django.contrib.sessions.middleware.SessionMiddleware',
'django.middleware.common.CommonMiddleware',
'django.middleware.csrf.CsrfViewMiddleware',
'django.contrib.auth.middleware.AuthenticationMiddleware',
'django.contrib.messages.middleware.MessageMiddleware',
'django.middleware.clickjacking.XFrameOptionsMiddleware',
"utils.md.KeLaMiddleware"
]
4.问题
-
中间件的功能好像有点像装饰器【底层源码闭包】
-
基于中间件可以做什么?
-
根据请求周期,对 request 进行赋值,后续方便进行调用。
-
根据请求周期,对业务逻辑代码进行自定义,决定是否可以继续向后
-
return None,继续向后走
-
return HttpResponse对象
return HttpResponse("...") return render("...") -> HttpResponse("...") return JsonReponse("...") -> HttpResponse("...")
-
-
根据请求周期,对返回给用户浏览器的数据进行自定义:删除内容、增加、cookie、响应头...
-
-
这个中间件和nginx apache这样的中间件概念一样吗?比如做前置代理,做https
Django中间件 / 拦截器 / RequestHanler
-
中间件可以跨语言调用吗?比如别人不是用python 写的,但是可以给我们的django 项目用?
Django中间件 ... 架构中间件: Django + redis(C语言)
-
中间件只要两层,不要中间那个process.riew行不行,是不是有些特定场合需要返回最后一层
...
-
那Django内置的中间件完成了些什么功能?
...
1.1.2 "不正常"
如果用户向我的网站请求时,如果访问URL:
-
/x1/
-
/x2/
-
/x3/ ,比如携带凭证token,有凭证继续,无凭证返回无权访问。
http://127.0.0.1:8000/x2/12/
http://127.0.0.1:8000/x2/12/?xxx=123
python
from django.utils.deprecation import MiddlewareMixin
from django.shortcuts import HttpResponse
class KeLaMiddleware(MiddlewareMixin):
def process_request(self, request):
# request.path_info
# print(request.path_info,"KeLa.process_request")
if request.path_info == "/x3/":
token = request.GET.get('token')
if token == "12938791923981723123":
return
else:
return HttpResponse("无权访问")
如果用户向我的网站请求时,如果访问URL:
-
/x1/
-
/x2/ ,比如携带凭证token,有凭证继续,无凭证返回无权访问。
x2/<int:v1>/', x2 http://127.0.0.1:8000/x1/10/ http://127.0.0.1:8000/x1/20/ http://127.0.0.1:8000/x1/11/
-
/x3/
python
class KeLaMiddleware(MiddlewareMixin):
def process_request(self, request):
# request.path_info
# print(request.path_info,"KeLa.process_request")
# 以x2开头 或 正则 /x2/1111/ /x2/10/
# if request.path_info == "/x2/":
if request.path_info.startswith("/x2/"):
token = request.GET.get('token')
if token == "12938791923981723123":
return
else:
return HttpResponse("无权访问")
python
class KeLaMiddleware(MiddlewareMixin):
def process_view(self, request, view, *args, **kwargs):
# request.path_info
# print(request.path_info,"KeLa.process_request")
url_name = request.resolver_match.url_name
if url_name == "x2":
token = request.GET.get('token')
if token == "12938791923981723123":
return
else:
return HttpResponse("无权访问")
关于自定义prcess_response,一般用于对请求要返回的数据进行修改。
python
class KeLaMiddleware(MiddlewareMixin):
def process_response(self, request, response):
response["xx"] = "wupeiqi"
return response
答疑
- Settings 里面的中间件有多个组件,那运行项目时的执行顺序是怎样的?是执行完这些中间件再执行路由匹配吗?后面写的中间件是不是要对前面的中间件功能非常清楚才行、避免可能功能覆盖带来bug?
- 這邊定義的響應頭在用戶下一次訪問的時候會帶上麽
- js可以读到content的内容吗
- 刚才讲的这个response返回值的修改,增加了一个"xx"="yiyebaitou",这种操作应该也可以增加的request请求头里面吧,那request增加的,是不是就和爬虫里面的某些js逆向参数,就是从这里来的?
1.2 使用(几乎不用)
-
编写类,在类型定义:process_request、process_view、process_response、process_exception、process_template_response
process_exception,视图函数有异常,处理出现异常时 process_template_response,对于视图函数返回内容渲染扩展。 - 在视图函数中如果返回的对象内部有一个render方法且可以被调用执行 - process_template_response返回response参数(返回值) - 在自定义的MyReponse的render方法中必须返回HttpRespose
-
中间件注册,在settings中的配置。
python
class KeLaMiddleware(MiddlewareMixin):
def process_exception(self, request, exception):
print(request)
print(exception, type(exception))
return HttpResponse("错误了")
python
def x1(request):
print("视图.x1")
return HttpResponse("x1")
python
class MyHttpResponse:
def __init__(self, body):
self.body = body
def render(self):
return HttpResponse(self.body) # 真正的返回
def x1(request):
print("视图.x1")
return MyHttpResponse("x1")
python
class KeLaMiddleware(MiddlewareMixin):
def process_template_response(self, request, response):
return response
python
def x1(request):
print("视图.x1")
return HttpResponse("源代码-x1")
def x2(request, v1):
return HttpResponse("源代码-x2")
def x3(request):
return HttpResponse("源代码-x3")
python
class MyHttpResponse:
def __init__(self, body):
self.body = body
def render(self):
return HttpResponse(self.body)
def x1(request):
print("视图.x1")
return MyHttpResponse("x1")
def x2(request, v1):
return MyHttpResponse("x2")
def x3(request):
return MyHttpResponse("x3")
python
class KeLaMiddleware(MiddlewareMixin):
def process_template_response(self, request, response):
response.body = f"源代码-{response.body}"
return response
1.3 源码
1.关于请求
python
from wsgiref.simple_server import make_server
def run_server(environ, start_response):
# 只要请求到来,就会走这里的代码
# 1.根据请求 environ 进行后续业务处理
# 2.返回内容。。。
start_response('200 OK', [('Content-Type', 'text/html')])
return [bytes('<h1>Hello, web!</h1>', encoding='utf-8'), ]
if __name__ == '__main__':
httpd = make_server('127.0.0.1', 8000, run_server) # # 有请求到来时,执行 obj(environ, start_response)
httpd.serve_forever()
python
from wsgiref.simple_server import make_server
class Handler:
def __init__(self):
# 做一些初始化动作
self.name = "wupeiqi"
def __call__(self,environ, start_response):
# 根据初始化的动作,去执行...
# ...
start_response('200 OK', [('Content-Type', 'text/html')])
return [bytes('<h1>Hello, web!</h1>', encoding='utf-8'), ]
if __name__ == '__main__':
obj = Handler() # 执行
httpd = make_server('127.0.0.1', 8000, obj) # 有请求到来时,执行 obj(environ, start_response)
httpd.serve_forever()
2.启动Django项目WSGIHandler.__init__
3.请求到来WSGIHandler.__call__
流程:中间件的执行、路由匹配、视图函数的执行。
小结
-
1.7.x源码,底层实现,是基于好几个列表。
-
4.x源码,
函数的作用域 + 闭包 + 装饰器 面向对象 + __call__方法 # 核心 # handler = SecurityMiddleware对象 # __call__ # process_request # get_reponse = SessionMiddleware对象 # process_response # __call__ # process_request # get_reponse = CommonMiddleware对象 # process_response # __call__ # process_request # get_reponse = KeLaMiddleware对象 # process_response
答疑
- 没悟透,不需要吾、只需要懂【不需要背+建立】
- 有些难
- 入门,听懂+能用(全家桶)
- 文档,用法没有源码。
- 源码,到底是怎么实现的功能(不修改、扩展)【*】
- 感觉听懂了,但又不清楚,这是不是学源码的正常情况,看B站视频写程序都很简单,也容易懂
- 课下还是得自己分析分析,一定会忘记
2.Cookie
本质上:保存在用户浏览器上键值对。
2.1 使用
python
from django.urls import path
from django.shortcuts import HttpResponse
def x1(request):
# 包含:响应体、响应头、状态码等信息
obj = HttpResponse("x1", status=201, reason="OK")
# 设置响应头
obj['name'] = "wupeiqi"
# 设置cookie
# import datetime
# ctime = datetime.datetime.now() + datetime.timedelta(seconds=10)
obj.set_cookie("v3", "root", max_age=10, path="/")
obj.set_cookie("v2", "hello")
obj.set_signed_cookie("info", "xiaoguang") # 签名
return obj
def x2(request):
print(request.COOKIES)
xx = request.get_signed_cookie("info") # 用户不能自己修改cookie的内容
print(xx)
# print(request.COOKIES.get('v1'))
# print(request.COOKIES.get('v2'))
return HttpResponse("x2")
urlpatterns = [
path('x1/', x1, name='x1'),
path('x2/', x2, name='x2'),
]
2.2 源码
-
HttpResponse,包裹
python# 包含:响应体、响应头、状态码等信息 obj = HttpResponse("x1", status=201, reason="OK") # 设置响应头 obj['name'] = "yiyebaitou" # 设置cookie # import datetime # ctime = datetime.datetime.now() + datetime.timedelta(seconds=10) obj.set_cookie("v3", "root", max_age=10, path="/") obj.set_cookie("v2", "hello") obj.set_signed_cookie("info", "xiaoguang") # 签名 return obj
-
WSGIRequest
pythonclass WSGIHandler(base.BaseHandler): request_class = WSGIRequest def __init__(self, *args, **kwargs): super().__init__(*args, **kwargs) self.load_middleware() def __call__(self, environ, start_response): set_script_prefix(get_script_name(environ)) signals.request_started.send(sender=self.__class__, environ=environ) request = self.request_class(environ)
pythonclass HttpRequest: def get_signed_cookie(self, key, default=RAISE_ERROR, salt="", max_age=None): cookie_value = self.COOKIES[key] value = signing.get_cookie_signer(salt=key + salt).unsign(cookie_value, max_age=max_age) return value class WSGIRequest(HttpRequest): def __init__(self, environ): self.environ = environ ... @cached_property def COOKIES(self): raw_cookie = get_str_from_wsgi(self.environ, "HTTP_COOKIE", "") return parse_cookie(raw_cookie)
3.Session
Session的使用一般依赖于Cookie,将一些数据不再发送值浏览器,而是保存的后端的服务器上。
3.1 使用
-
Session到底要存储到哪里?默认数据库。
pythonINSTALLED_APPS = [ 'django.contrib.admin', 'django.contrib.auth', 'django.contrib.contenttypes', # 'django.contrib.sessions', # sessions功能的APP django_session 'django.contrib.messages', 'django.contrib.staticfiles', ]
pythonMIDDLEWARE = [ 'django.middleware.security.SecurityMiddleware', 'django.contrib.sessions.middleware.SessionMiddleware', # process_request/process_response 'django.middleware.common.CommonMiddleware', 'django.middleware.csrf.CsrfViewMiddleware', 'django.contrib.auth.middleware.AuthenticationMiddleware', 'django.contrib.messages.middleware.MessageMiddleware', 'django.middleware.clickjacking.XFrameOptionsMiddleware', # "utils.md.KeLaMiddleware", ]
python############ # SESSIONS # ############ # Session存储在哪里? SESSION_ENGINE = "django.contrib.sessions.backends.db" # 如果存储到文件中,文件的路径。 SESSION_ENGINE = "django.contrib.sessions.backends.file" SESSION_FILE_PATH = None # 存储到缓存 SESSION_ENGINE = "django.contrib.sessions.backends.cache" SESSION_CACHE_ALIAS = "default" # 存储到缓存 + 数据库 SESSION_ENGINE = "django.contrib.sessions.backends.cache_db" SESSION_CACHE_ALIAS = "default" # 存储到cookie SESSION_ENGINE = "django.contrib.sessions.backends.signed_cookies" # class to serialize session data SESSION_SERIALIZER = "django.contrib.sessions.serializers.JSONSerializer" # ------------------------------- # Cookie name. This can be whatever you want. SESSION_COOKIE_NAME = "sessionid" # Age of cookie, in seconds (default: 2 weeks). SESSION_COOKIE_AGE = 60 * 60 * 24 * 7 * 2 # A string like "example.com", or None for standard domain cookie. SESSION_COOKIE_DOMAIN = None # Whether the session cookie should be secure (https:// only). SESSION_COOKIE_SECURE = False # The path of the session cookie. SESSION_COOKIE_PATH = "/" # Whether to use the HttpOnly flag. SESSION_COOKIE_HTTPONLY = True # Whether to set the flag restricting cookie leaks on cross-site requests. # This can be 'Lax', 'Strict', 'None', or False to disable the flag. SESSION_COOKIE_SAMESITE = "Lax" # Whether to save the session data on every request. SESSION_SAVE_EVERY_REQUEST = False # Whether a user's session cookie expires when the web browser is closed. SESSION_EXPIRE_AT_BROWSER_CLOSE = False
注意:如果是非数据库,可以主调用app的注册代码部分。
-
请求=登录,生成Session、Cookie。
-
再次请求,默认携带cookie,根据Cookie中的凭证,去找到Session中原本存储的数据。
request.session['id'] = 999 request.session['id'] = 88 request.session.get("id") # del request.session['id'] # request.session.clear()
pythonfrom django.urls import path from django.shortcuts import HttpResponse def x1(request): request.session['id'] = 999 request.session['name'] = 'wupeiqi' request.session['age'] = '25' return HttpResponse("x1") def x2(request): print(request.session.get("id")) print(request.session.get("name")) print(request.session.get("age")) return HttpResponse("x2") urlpatterns = [ path('x1/', x1, name='x1'), path('x2/', x2, name='x2'), ]
3.2 源码
1.引擎配置
-
数据库引擎
pythonSESSION_ENGINE = "django.contrib.sessions.backends.db"
pythonINSTALLED_APPS = [ 'django.contrib.sessions', 'django.contrib.messages', 'django.contrib.staticfiles', ]
>>>python manage.py makemigrations >>>python manage.py migrate
-
文件
# 如果存储到文件中,文件的路径。 SESSION_ENGINE = "django.contrib.sessions.backends.file" SESSION_FILE_PATH = None INSTALLED_APPS = [ #'django.contrib.sessions', 'django.contrib.messages', 'django.contrib.staticfiles', ]
2.中间件
python
MIDDLEWARE = [
'django.middleware.security.SecurityMiddleware',
'django.contrib.sessions.middleware.SessionMiddleware', # 必须设置
'django.middleware.common.CommonMiddleware',
'django.middleware.csrf.CsrfViewMiddleware',
...
]
2.1 创建对象
在启动django程序时,会自动创建 SessionMiddlewared对象。
python
class MiddlewareMixin:
def __init__(self, get_response):
self.get_response = get_response
class SessionMiddleware(MiddlewareMixin):
def __init__(self, get_response):
super().__init__(get_response)
# "django.contrib.sessions.backends.db" "django.contrib.sessions.backends.file"
engine = import_module(settings.SESSION_ENGINE)
# db.SessionStore file.SessionStore
self.SessionStore = engine.SessionStore
2.2 请求到来 *
python
def process_request(self, request):
# 1.去Cookie中读取凭证 mid="123123123123"
session_key = request.COOKIES.get(settings.SESSION_COOKIE_NAME)
# 2.实例化
request.session = self.SessionStore(session_key)
python
def x1(request):
# request.session -> file.SessionStore() /
request.session['id'] = 999
request.session['name'] = 'wupeiqi' 类中的__setitem__
request.session['age'] = '25'
return HttpResponse("x1")
2.3 请求结束 *
...
总结
- 使用角度:
- 中间件
- Cookie
- Session:Cookie + 中间件
- 源码流程:
- 中间件、cookie、session
答疑
-
老师,cookie过期时间设置以后,请求的时候是在哪块判断的cookie是否过期
data = request.COOKIES.get("v1") # 过期或未设置
-
老师 那session以文件方式存储,那每次运行都会覆盖上一次的吗
- 覆盖
- 是否变更
-
每个浏览器应该是不同的文件吧
-
有个基础知识问题:response.Item这里的干什么的?
-
一个用户ID 是不是只会 对应一个 session,比如更换浏览器访问,后台就会被变更了 对吧
A浏览器 B浏览器