Getting Headers from a Ruby Net::Http Request Before Making the Request

Ruby - Send GET request with headers

Using net/http as suggested by the question.

References:

Net::HTTP https://ruby-doc.org/stdlib-2.4.1/libdoc/net/http/rdoc/Net/HTTP.html
Net::HTTP::get https://ruby-doc.org/stdlib-2.4.1/libdoc/net/http/rdoc/Net/HTTP.html#method-c-get
Setting headers: https://ruby-doc.org/stdlib-2.4.1/libdoc/net/http/rdoc/Net/HTTP.html#class-Net::HTTP-label-Setting+Headers
Net::HTTP::Get https://ruby-doc.org/stdlib-2.4.1/libdoc/net/http/rdoc/Net/HTTP/Get.html
Net::HTTPGenericRequest https://ruby-doc.org/stdlib-2.4.1/libdoc/net/http/rdoc/Net/HTTPGenericRequest.html and Net::HTTPHeader https://ruby-doc.org/stdlib-2.4.1/libdoc/net/http/rdoc/Net/HTTPHeader.html (for methods that you can call on Net::HTTP::Get)

So, for example:

require 'net/http'    

uri = URI("http://www.ruby-lang.org")
req = Net::HTTP::Get.new(uri)
req['some_header'] = "some_val"

res = Net::HTTP.start(uri.hostname, uri.port, use_ssl: uri.scheme == 'https') { |http|
  http.request(req)
}

puts res.body # <!DOCTYPE html> ... </html> => nil

Note: if your response has HTTP result state 301 (Moved permanently), see Ruby Net::HTTP - following 301 redirects

Ruby NET::HTTP Read the header BEFORE the body (without HEAD request)?

net/http supports streaming, you can use this to read the header before the body.

Code example,

url = URI('http://stackoverflow.com/questions/41306082/ruby-nethttp-read-the-header-before-the-body-without-head-request')

Net::HTTP.start(url.host, url.port) do |http|
  request = Net::HTTP::Get.new(url)
  http.request(request) do |response|

    # check headers here, body has not yet been read
    # then call read_body or just body to read the body

    if true  
      response.read_body do |chunk|
        # process body chunks here
      end
    end
  end
end

Show headers and body text of an HTTP request in Ruby

The #to_hash method of a request object may be useful. Here's an example to build a GET request and inspect headers:

require 'net/http'
require 'uri'

uri = URI('http://example.com/cached_response')
req = Net::HTTP::Get.new(uri.request_uri)

req['X-Crazy-Header'] = "This is crazy"

puts req.to_hash # hash of request headers
# => {"accept"=>["*/*"], "user-agent"=>["Ruby"], "x-crazy-header"=>["This is crazy"]}

And an example for a POST request to set form data and inspect headers and body:

require 'net/http'
require 'uri'

uri = URI('http://www.example.com/todo.cgi')
req = Net::HTTP::Post.new(uri.path)

req.set_form_data('from' => '2005-01-01', 'to' => '2005-03-31')

puts req.to_hash # hash of request headers
# => {"accept"=>["*/*"], "user-agent"=>["Ruby"], "content-type"=>["application/x-www-form-urlencoded"]}

puts req.body # string of request body
# => from=2005-01-01&to=2005-03-31

how do I include a header in an http request in ruby

get_response is a shorthand for making a request, when you need more control - do a full request yourself.

There's an example in ruby standard library here:

uri = URI.parse("http://www.ncdc.noaa.gov/cdo-web/api/v2/datasets/")
req = Net::HTTP::Get.new(uri)
req['token'] = 'fjhKJFSDHKJHjfgsdfdsljh'

res = Net::HTTP.start(uri.hostname, uri.port) {|http|
  http.request(req)
}

Get response headers from Ruby HTTP request

The response object actually contains the headers.

See "Net::HTTPResponse" for more infomation.

You can do:

response['Cache-Control']

You can also call each_header or each on the response object to iterate through the headers.

If you really want the headers outside of the response object, call response.to_hash

How to make an HTTP GET with modified headers?

Created a solution that worked for me (worked very well) - this example getting a range offset:

require 'uri'
require 'net/http'

size = 1000 #the last offset (for the range header)
uri = URI("http://localhost:80/index.html")
http = Net::HTTP.new(uri.host, uri.port)
headers = {
    'Range' => "bytes=#{size}-"
}
path = uri.path.empty? ? "/" : uri.path

#test to ensure that the request will be valid - first get the head
code = http.head(path, headers).code.to_i
if (code >= 200 && code < 300) then

    #the data is available...
    http.get(uri.path, headers) do |chunk|
        #provided the data is good, print it...
        print chunk unless chunk =~ />416.+Range/
    end
end