The HTTP Gem*

*NOTE: this gem has the worst name in the history of SEO. But perhaps we can fix that if we all refer to it as "The HTTP Gem". Entering that phrase into Google actually pulls it up as #4 for me!

The HTTP Gem is an easy-to-use client library for making requests from Ruby. It uses a simple method chaining system for building requests, similar to libraries like JQuery or Python's Requests.

Installation

Add this line to your application's Gemfile:

gem 'http'

And then execute:

$ bundle

Or install it yourself as:

$ gem install http

Inside of your Ruby program do:

require 'http'

...to pull it in as a dependency.

Making Requests

Let's start with getting things:

>> HTTP.get("http://www.google.com")
=> "<html><head><meta http-equiv=\"content-type\" content=..."

That's it! The result is the response body as a string. To obtain an HTTP::Response object instead of the response body, chain .response on the end of the request:

>> HTTP.get("http://www.google.com").response
=> #<HTTP/1.0 200 OK @headers={"Content-Type"=>"text/html; charset=UTF-8", "Date"=>"Fri, ...>

Making POST requests is simple too. Want to POST a form?

HTTP.post "http://example.com/resource", :form => {:foo => "42"}

Making GET requests with query string parameters is as simple.

HTTP.get "http://example.com/resource", :params => {:foo => "bar"}

Want to POST with a specific body, JSON for instance?

HTTP.post "http://example.com/resource", :body => JSON.dump(:foo => '42')

Or have it serialize JSON for you:

HTTP.post "http://example.com/resource", :json => {:foo => '42'}

It's easy!

Adding Headers

The HTTP library uses the concept of chaining to simplify requests. Let's say you want to get the latest commit of this library from Github in JSON format. One way we could do this is by tacking a filename on the end of the URL:

HTTP.get "https://github.com/tarcieri/http/commit/HEAD.json"

The Github API happens to support this approach, but really this is a bit of a hack that makes it easy for people typing URLs into the address bars of browsers to perform the act of content negotiation. Since we have access to the full, raw power of HTTP, we can perform content negotiation the way HTTP intends us to, by using the Accept header:

HTTP.with_headers(:accept => 'application/json').
  get("https://github.com/tarcieri/http/commit/HEAD")

This requests JSON from Github. Github is smart enough to understand our request and returns a response with Content-Type: application/json. If you happen to have a library loaded which defines the JSON constant and implements JSON.parse, the HTTP library will attempt to parse the JSON response.

Shorter aliases exists for HTTP.with_headers:

HTTP.with(:accept => 'application/json').
  get("https://github.com/tarcieri/http/commit/HEAD")

HTTP[:accept => 'application/json'].
  get("https://github.com/tarcieri/http/commit/HEAD")

Content Negotiation

As important a concept as content negotiation is HTTP, it sure should be easy, right? But usually it's not, and so we end up adding ".json" onto the ends of our URLs because the existing mechanisms make it too hard. It should be easy:

HTTP.accept(:json).get("https://github.com/tarcieri/http/commit/HEAD")

This adds the appropriate Accept header for retrieving a JSON response for the given resource.

Contributing to HTTP