How to translate a POST request in curl into ruby?

Question

I have this post request :

curl -i -X POST \
   -H "Accept:application/json" \
   -H "content-type:application/x-www-form-urlencoded" \
   -d "disambiguator=Document&confidence=-1&support=-1&text=President%20Obama%20called%20Wednesday%20on%20Congress%20to%20extend%20a%20tax%20break%20for%20students%20included%20in%20last%20year%27s%20economic%20stimulus%20package" \
   http://spotlight.dbpedia.org/dev/rest/annotate/

How can I write it in ruby? I tried this as Kyle had suggested:

require 'rubygems'
require 'net/http'
require 'uri'

uri = URI.parse('http://spotlight.dbpedia.org/rest/annotate')

http = Net::HTTP.new(uri.host, uri.port)

request = Net::HTTP::Post.new(uri.request_uri)
request.set_form_data({
                      "disambiguator" => "Document",
                      "confidence"    => "0.3",
                      "support"       => "0",
                      "text"          => "President Obama called Wednesday on Congress to extend a tax break for students included in last year's economic stimulus package"
                      })

request.add_field("Accept", "application/json")
request.add_field("Content-Type", "application/x-www-form-urlencoded")

response = http.request(request)
puts response.inspect

but got this error:

#<Net::HTTPInternalServerError 500 Internal Error readbody=true>

Answer 1

You've since modified your question to include my initial response. In my initial answer, adding in the 'Content-Type' header causes it to be duplicated, remove the adding of that header and your example should work:

This Cheat Sheet describes how to provide parameters to HTTP posts:

require 'rubygems'
require 'net/http'
require 'uri'

uri = URI.parse('http://spotlight.dbpedia.org/rest/annotate/')

http = Net::HTTP.new(uri.host, uri.port)

request = Net::HTTP::Post.new(uri.request_uri)
request.set_form_data({
  "disambiguator" => "Document",
  "confidence"    => "0.25",
  "support"       => "0",
  "text"          => "President Obama called Wednesday on Congress to extend a tax break for students included in last year's economic stimulus package"
})

request.add_field("Accept", "application/json")

response = http.request(request)
puts response.inspect

I tested this (on a Linux system) by setting the url to 'http://localhost:9999' and running netcat from another terminal:

$ cat resp.txt
HTTP 200 OK


$ nc -l 9999 < resp.txt
POST /this/that HTTP/1.1
Content-Length: 223
Content-Type: application/x-www-form-urlencoded, application/x-www-form-urlencoded
Connection: close
Accept: */*, application/json
Host: localhost:9999

disambiguator=Document&confidence=0.25&support=0&text=President%20Obama%20called%20Wednesday%20on%20Congress%20to%20extend%20a%20tax%20break%20for%20students%20included%20in%20last%20year%27s%20economic%20stimulus%20package

This should cover both of your needs: sending form parameters as well as setting http headers.

EDIT- By 0x90:

that is what should be done:

request.add_field("Accept", "application/json")

request.set_form_data({
  "disambiguator" => "Document",
  "confidence"    => "0.3",
  "support"       => "0",
  "text"          => "President Obama called Wednesday on Congress to extend a tax break for students included in last year's economic stimulus package",
  "Content-Type" => "application/x-www-form-urlencoded"
})