How to set content-type in a POST request in R?

Question

I have to make a post request. The problem is, the application that is exposing it's api as webservice, has set it's Content-Type to "text/plain". I tried RCurl package and httpRequest package but could not figure out how to set the content-type. I tried to directly make a postrequest to a URL that did not have that content-type, then postForm worked. Any help here?

EDIT: I will try to explain what I need to do here. I have an url. I need to make POST requests to it by passing it some parameters something like this

POST to "url/agents/where/agent?="Smith"

This is what you would type if you use the REST console extension on chrome for making webservice calls. I need to make this from R by setting the content-type to "text/plain"

What I have tried is this,

postForm("url/agents/get/all")

This works like a charm as say in our case the webservice call for calling all the agents does not require the content-type to be "text/plain" and also does not require any parameters to be passed to it(eg. no particular agent name as I want all of them). I think I have figured out how to pass a parameter by giving name value pairs in a list to .opts. What I am not able to figure out is how to set content-type.

I have tried this but it failed,

postForm("url/agents/where",
         .opts = list(postfields = toJSON(list("name" = "Smith")),
         httpheader = c('Content-Type' = 'text/plain', ssl.verifypeer = FALSE)))

Answer 1

It would be helpful to have the code that you've tried, but the general answer is that you can specify it in the httpheader argument to curlPerform. Here's a slightly modified version from the documentation:

h <- basicTextGatherer()
h$reset()
curlPerform(url,
            httpheader=c('Content-Type' = "text/plain"),
            postfields=toJSON(list("name" = "Smith")),
            customrequest = 'POST', 
            writefunction = h$update,
            verbose = TRUE,
            ssl.verifypeer = FALSE)
body <- h$value()