如何使用Cookie与RCurl？ [英] How do I use cookies with RCurl?

问题描述

我想写一个R包，通过REST API访问一些数据。但是，API不使用http验证，而是依靠Cookie来保存会话的凭据。

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.

本质上，我想替换以下两个来自带有两个R函数的bash脚本的行：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

我显然不理解RCurl如何使用curl选项。我的脚本现在有：

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)

最后的 getURL（）失败，并从服务器发出未登录消息，并且 postForm（）

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

在 一般来说，你不需要创建一个cookie文件，除非你想学习这些cookie。

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

实际上，web服务器使用代理数据，重定向和隐藏的帖子数据，但这应该有助于：

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，通常可以隐藏发布数据。要捕获它，你可能想要，例如。在Chrome中使用开发人员工具（ Ctrl Shift I ） - > 网络选项卡，以显示发布字段名称和值。

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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