Ruby Net::HTTP passing headers through the creation of request - ruby

Question

Maybe I'm just blind but many post about passing headers in Net::HTTP follows the lines of
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) {|http|
http.request(req)
}
puts res.body
(From Ruby - Send GET request with headers metaphori's answer)
And from the Net::HTTP docs (https://docs.ruby-lang.org/en/2.0.0/Net/HTTP.html)
uri = URI('http://example.com/cached_response')
file = File.stat 'cached_response'
req = Net::HTTP::Get.new(uri)
req['If-Modified-Since'] = file.mtime.rfc2822
res = Net::HTTP.start(uri.hostname, uri.port) {|http|
http.request(req)
}
open 'cached_response', 'w' do |io|
io.write res.body
end if res.is_a?(Net::HTTPSuccess)
But what is the advantage of doing the above when you can pass the headers via the following way?
options = {
'headers' => {
'Content-Type' => 'application/json'
}
}
request = Net::HTTP::Get.new('http://www.stackoverflow.com/', options['headers'])
This allows you to parameterize the headers and can allow for multiple headers very easily.
My main question is, what is the advantage of passing the headers in the creation of Net::HTTP::Get vs passing them after the creation of Net::HTTP::Get
Net::HTTPHeader already goes ahead and assigns the headers in the function
def initialize_http_header(initheader)
#header = {}
return unless initheader
initheader.each do |key, value|
warn "net/http: duplicated HTTP header: #{key}", uplevel: 1 if key?(key) and $VERBOSE
if value.nil?
warn "net/http: nil HTTP header: #{key}", uplevel: 1 if $VERBOSE
else
value = value.strip # raise error for invalid byte sequences
if value.count("\r\n") > 0
raise ArgumentError, 'header field value cannot include CR/LF'
end
#header[key.downcase] = [value]
end
end
end
So doing
request['some_header'] = "some_val" almost seems like code duplication.

Answer 1

There is no advantage for setting headers one way or another, at least not that I can think of. It comes down to your own preference. In fact, if you take a look at what happens when you supply headers while initializing a new Net::Http::Get, you will find that internally, Ruby simply sets the headers onto a #headers variable:
https://github.com/ruby/ruby/blob/c5eb24349a4535948514fe765c3ddb0628d81004/lib/net/http/header.rb#L25
And if you set the headers using request[name] = value, you can see that Net::Http does the exact same thing, but in a different method:
https://github.com/ruby/ruby/blob/c5eb24349a4535948514fe765c3ddb0628d81004/lib/net/http/header.rb#L46
So the resulting object has the same configuration no matter which way you decide to pass the request headers.