如何通过 RCurl 使用 cookie? [英] How do I use cookies with RCurl?

问题描述

我正在尝试编写一个通过 REST API 访问一些数据的 R 包.但是，该 API 不使用 http 身份验证，而是依靠 cookie 来保存会话凭据.

I am trying to write an R package that accesses some data via a REST API. The API, however, doesn't use http authentication, but rather relies on cookies to keep credentials with the session.

基本上，我想用两个 R 函数替换 bash 脚本中的以下两行:一个用于执行登录，并存储会话 cookie，第二个用于获取数据.

Essentially, I'd like to replace the following two lines from a bash script with two R functions: One to perform the login, and store the session cookie, and the second to GET the data.

curl -X POST -c cookies.txt -d"username=xxx&password=yyy" http://api.my.url/login
curl         -b cookies.txt                               http://api.my.url/data

我显然不明白 RCurl 如何处理 curl 选项.我的脚本目前有:

I'm clearly not understanding how RCurl works with curl options. My script as it stands has:

library(RCurl)
curl <- getCurlHandle()
curlSetOpt(cookiejar='cookies.txt', curl=curl)
postForm("http://api.my.url/login", username='xxx', password='yyy', curl=curl)
getURL('http://api.my.url/data", curl=curl)

最终的 getURL() 失败并显示未登录".来自服务器的消息，并且在 postForm() 之后不存在 cookies.txt 文件.

The final getURL() fails with a "Not logged in." message from the server, and after the postForm() no cookies.txt file exists.

推荐答案

一般情况下你不需要创建 cookie 文件，除非你想研究 cookie.

In general you don't need to create a cookie file, unless you want to study the cookies.

鉴于此，实际上，Web 服务器使用代理数据、重定向和隐藏的帖子数据，但这应该会有所帮助:

Given this, in real word, web servers use agent data, redirecting and hidden post data, but this should help:

library(RCurl)

#Set your browsing links 
loginurl = "http://api.my.url/login"
dataurl  = "http://api.my.url/data"

#Set user account data and agent
pars=list(
     username="xxx"
     password="yyy"
)
agent="Mozilla/5.0" #or whatever 

#Set RCurl pars
curl = getCurlHandle()
curlSetOpt(cookiejar="cookies.txt",  useragent = agent, followlocation = TRUE, curl=curl)
#Also if you do not need to read the cookies. 
#curlSetOpt(  cookiejar="", useragent = agent, followlocation = TRUE, curl=curl)

#Post login form
html=postForm(loginurl, .params = pars, curl=curl)

#Go wherever you want
html=getURL(dataurl, curl=curl)

#Start parsing your page
matchref=gregexpr("... my regexp ...", html)

#... .... ...

#Clean up. This will also print the cookie file
rm(curl)
gc()

重要

除了用户名和密码之外，通常还有隐藏的帖子数据.要捕获它，您可能想要，例如在 Chrome 中，使用 Developer tools (Ctrl Shift I) -> Network Tab，以显示帖子字段名称和值.

Important

There can often be hidden post data, beyond username and password. To capture it you may want, e.g. in Chrome, to use Developer tools (Ctrl Shift I) -> Network Tab, in order to show the post field names and values.

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