前言
参数关联是接口测试和性能测试最为重要的一个步骤，很多接口的请求参数是动态的，并且需要从上一个接口的返回值里面取出来，一般只能用一次就失效了。
最常见的案例就是网站的登录案例，很多网站的登录并不仅仅只传username和psw两个参数，往往有其它的动态参数。
有时候还需要带上cookies参数，如JSESSIONID
登录参数
首先分析下目标网站【学信网：https://account.chsi.com.cn/passport/login】的登录接口请求参数。
先输入账号和密码，点击登录，使用fiddler工具抓包查看请求参数，用两个参数是网页自动给的参数（用户没输入）
| lt | LT-945609-OlQbFZ4LfFeW4gWBgJAJAbBVxwVyy7-cas |
| execution | f8947218-de8d-4062-88a9-99e761aff8b4_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 |
退出用户后，重复上面操作，再抓包看请求参数，会发现变了
| lt | LT-946015-AtfP7ic5GSmqHffGpQbZYbv9shggDb-cas |
| execution | 73284ef4-b155-41cf-8924-c2137733a22d_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 |
获取接口返回数据
我们想登录的话，必须先得到 lt 和 execution 这2个参数，那么问题来了：这两个参数是从哪来的？
打开登录页面https://account.chsi.com.cn/passport/login直接刷新，看返回的html内容
接下来我们可以用lxml爬虫etree，从html中解析出 lt 的 value 和 execution 的 value 这两个值
import requests,urllib3,os
from bs4 import BeautifulSoup
urllib3.disable_warnings()
from lxml import etree
#初始化会话
s = requests.Session()
def get_execution_it():
result = {}
url = "https://account.chsi.com.cn/passport/login"
# 登录get方法，不用传入cookie
header = {
"User-Agent": "Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/73.0.3683.103 Safari/537.36"
}
s.headers.update(header)
r = s.get(url,verify=False)
# print(r.content.decode("utf-8"))
html = etree.HTML(r.content.decode("utf-8"))
# print(html)
# tag = html.find(class_="cr_top_my")
# print(len(tag))
try:
result["lt"] = html.xpath('//input[@name="lt"]')[0].get("value")
result["execution"] = html.xpath('//input[@name="execution"]')[0].get("value")
print(result)
except:
print("获取1t/execution失败")
return result
if __name__ == '__main__':
result = get_execution_it()
JSESSIONID
登录里面实际上会有一个非常重要的cookies参数，JSESSIONID=A7E6B911CD6E59123F657784E5BDD7B3，这个JSESSIONID也是动态的，每次重新打开页面都会变。
这个参数也是第一次访问登录页面时候，服务器会自动返回过来的，使用浏览器无痕模式首次访问就能抓取到了。
cookies参数关联实现就非常简单了，直接用requests.session()去发个get请求就能自动保存了，所以上一步get_it_execution()实际上也同步了cookies参数。
参考代码：
import requests,urllib3,os
from bs4 import BeautifulSoup
urllib3.disable_warnings()
from lxml import etree
#初始化会话
s = requests.Session()
def get_execution_it():
result = {}
url = "https://account.chsi.com.cn/passport/login"
# 登录get方法，不用传入cookie
header = {
"User-Agent": "Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/73.0.3683.103 Safari/537.36"
}
s.headers.update(header)
r = s.get(url,verify=False)
# print(r.content.decode("utf-8"))
html = etree.HTML(r.content.decode("utf-8"))
# print(html)
# tag = html.find(class_="cr_top_my")
# print(len(tag))
try:
result["lt"] = html.xpath('//input[@name="lt"]')[0].get("value")
result["execution"] = html.xpath('//input[@name="execution"]')[0].get("value")
print(result)
except:
print("获取1t/execution失败")
return result
def login(result,user=None,passwd=None):
loginurl = "https://account.chsi.com.cn/passport/login"
headers = {
"Referer":loginurl,
"User-Agent":"Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/73.0.3683.103 Safari/537.36",
"Content-Type":"application/x-www-form-urlencoded",
"Upgrade-Insecure-Requests":"1",
"Accept":"text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3",
"Origin":"https://account.chsi.com.cn",
"Content-Length":"3934",
"Cache-Control":"max-age=0"
}
body = {
"username":user,
"password":passwd,
"submit":"登录",
"lt":result["lt"],
"execution":result["execution"],
"_eventId":"submit"
}
s.headers.update(headers)
r1 = s.post(url=loginurl,headers=headers,data=body,verify=False)
print(r1.text)
if __name__ == '__main__':
result = get_execution_it()
# login(result,user="自己学信网的账号",passwd="自己学信网的密码")