Convert curl code into R via the RCurl package?

Question

How I would write the following curl POST method using R and the RCurl package?

curl -k -u myusername:mypassword -d '{"text":"Hello World!","level":"Noob"}' -H "Content-Type: application/json" -H "Accept: application/json" "http://api.website/v1/access?"

Answer 1

FINAL EDIT: After emailing the great Duncan Temple Lang I have a solution:

library(RCurl)
library(RJSONIO)
postForm("http://api.website/v1/access?",
         .opts = list(postfields = toJSON(list(text = "Hello World!", level = "Noob")),
                      httpheader = c('Content-Type' = 'application/json', Accept = 'application/json'),
                      userpwd = "Username:Password",
                      ssl.verifypeer = FALSE))

My previous post is below but it has all now been superseded by the edit above (I've left the below for reference):

I would like to know the answer to this question myself. even looking at TARehman's answer I still can't work out how to do it (my lack of understanding is no doubt the root).

If you download curl from its website (I used the generic-win binary version), then here's one way of doing it in R via the 'system' command which is like using the window's command line window but from R:

output <- system('C:/+/curl-7.27.0-rtmp-ssh2-ssl-sspi-zlib-idn-static-bin-w32/curl  -k -u "username:password" -d "{\\"text\\":\\"Hello World!\\",\\"level\\":\\"Noob\\"}" -H "Content-Type: application/json" -H "Accept: application/json" "http://api.website/v1/access?"', intern = TRUE))

The above works with one of the API's I use. You can then use

I really hope you find an answer because it would be useful for me to know too.

EDIT: My attempt using an actual API with RCurl via @TARehman's example:

Here is the curl code which works fine:

x = system('C:/+/curl-7.27.0-rtmp-ssh2-ssl-sspi-zlib-idn-static-bin-w32/curl  -k -u "USERNAME:PASSWORD" -d "{\\"text\\":\\"Have a nice day!\\"}" -H "Content-Type: application/json" -H "Accept: application/json" "http://api.theysay.io:60000/v1/sentiment?"', intern = TRUE)

And here is how I've rewritten it in RCurl:

curl.opts <- list(userpwd = "username:password", 
                  httpheader = "Content-Type: application/json",
                  httpheader = "Accept: application/json",
                  timeout = 20, 
                  connecttimeout = 20, 
                  verbose = TRUE, 
                  useragent = "RCurl",
                  cainfo = system.file("CurlSSL", "cacert.pem", package = "RCurl"))

postForm("http://api.theysay.io:60000/v1/sentiment?", .params = c(data = '{\\"text\\":\\"Have a nice day!\\"}'), .opts = curl.opts)

This however did not work and results in the following (clearly I have not understood something correctly):

* About to connect() to api.theysay.io port 60000 (#0)
*   Trying 163.1.94.100... * connected
* Connected to api.theysay.io (163.1.94.100) port 60000 (#0)
> POST /v1/sentiment? HTTP/1.1
User-Agent: RCurl
Host: api.theysay.io:60000
Accept: application/json
Content-Length: 193
Expect: 100-continue
Content-Type: multipart/form-data; boundary=----------------------------7620b19c7a5d

< HTTP/1.1 100 Continue
< HTTP/1.1 401 Unauthorized
< WWW-Authenticate: Basic realm="Secured Resource"
< Content-Type: text/plain
< Server: spray-can/1.0-M2.1
< Date: Wed, 12 Sep 2012 12:26:06 GMT
< Content-Length: 77
< 
* Ignoring the response-body
* Connection #0 to host api.theysay.io left intact
* Issue another request to this URL: 'http://api.theysay.io:60000/v1/sentiment?'
* Re-using existing connection! (#0) with host api.theysay.io
* Connected to api.theysay.io (163.1.94.100) port 60000 (#0)
* Server auth using Basic with user '[USERNAME]'
> POST /v1/sentiment? HTTP/1.1
Authorization: Basic [KEY]==
User-Agent: RCurl
Host: api.theysay.io:60000
Accept: application/json
Content-Length: 193
Expect: 100-continue
Content-Type: multipart/form-data; boundary=----------------------------949d191bdaeb

< HTTP/1.1 100 Continue
< HTTP/1.1 415 Unsupported Media Type
< Content-Type: text/plain
< Server: spray-can/1.0-M2.1
< Date: Wed, 12 Sep 2012 12:26:06 GMT
< Content-Length: 93
< 
* Connection #0 to host api.theysay.io left intact
[1] "There was a problem with the requests Content-Type:\nExpected 'text/xml' or 'application/json'"
attr(,"Content-Type")

"text/plain"