Python：尝试使用请求发布表单

Question

我正在尝试使用Python和请求库登录网站以进行某些抓取，但我正在尝试以下操作（无效）：

import requests
headers = {'User-Agent': 'Mozilla/5.0'}
payload = {'username':'niceusername','password':'123456'}

In [12]: r = requests.post('https://admin.example.com/login.php',headers=headers,data=payload)

但是，nada，重定向到登录页面。我需要打开一个会话吗？我执行了错误的POST请求，是否需要加载cookie？还是会话会自动执行？我在这里迷路了，需要一些帮助和解释。

我要登录的网站是php，我是否需要“捕获set-
cookie并设置cookie标头”？如果是这样，我不知道该怎么做。该网页是具有以下内容的表单（如果有帮助）：输入：username’‘password’‘id’：’myform’，’action’：“
login.php

一些额外的信息，也许您可​​以在这里看到我所缺少的..

In [13]: r.headers
Out[13]: CaseInsensitiveDict({'content-encoding': 'gzip', 'transfer-encoding': 'chunked',
 'set-cookie': 'PHPSESSID=v233mnt4malhed55lrpc5bp8o1; path=/',
  'expires': 'Thu, 19 Nov 1981 08:52:00 GMT', 'vary': 'Accept-Encoding', 'server': 'nginx',
   'connection': 'keep-alive', 'pragma': 'no-cache',
    'cache-control': 'no-store, no-cache, must-revalidate, post-check=0, pre-check=0',
     'date': 'Tue, 24 Dec 2013 10:50:44 GMT', 'content-type': 'text/html'})

In [14]: r.cookies
Out[14]: <<class 'requests.cookies.RequestsCookieJar'>[Cookie(version=0, name='PHPSESSID',
 value='v233mnt4malhed55lrpc5bp8o1', port=None, port_specified=False, domain='admin.example.com',
  domain_specified=False, domain_initial_dot=False, path='/', path_specified=True, secure=False,
   expires=None, discard=True, comment=None, comment_url=None, rest={}, rfc2109=False)]>

我非常感谢您的帮助，谢谢！

更新，感谢atupal的回答：

    import requests

headers = {'User-Agent': 'Mozilla/5.0'}
payload = {'username':'usr','pass':'123'}
link    = 'https://admin.example.com/login.php'
session = requests.Session()
resp    = session.get(link,headers=headers)
# did this for first to get the cookies from the page, stored them with next line:
cookies = requests.utils.cookiejar_from_dict(requests.utils.dict_from_cookiejar(session.cookies))
resp    = session.post(link,headers=headers,data=payload,cookies =cookies)
#used firebug to check POST data, password, was actually 'pass', under 'net' in param.  
#and to move forward from here after is:
session.get(link)

Answer 1

您可以使用Session对象

import requests
headers = {'User-Agent': 'Mozilla/5.0'}
payload = {'username':'niceusername','password':'123456'}

session = requests.Session()
session.post('https://admin.example.com/login.php',headers=headers,data=payload)
# the session instance holds the cookie. So use it to get/post later.
# e.g. session.get('https://example.com/profile')