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A gem for turning URLs into website previews
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Onebox is a library for turning media URLs into simple HTML previews of the resource.

Onebox currently has support for page, image, and video URLs for many popular sites.

It's great if you want users to input URLs and have your application convert them into rich previews for display. For example, a link to a YouTube video would be automatically converted into a video player.

It was originally created for Discourse but has since been extracted into this convenient gem for all to use!


Using onebox is fairly simple! First, make sure the library is required:

require "onebox"

Then pass a link to the library's interface:

require "onebox"

url = ""
preview = Onebox.preview(url)

This will contain a simple Onebox::Preview object that handles all the transformation. From here you either call Onebox::Preview#to_s or just pass the object to a string:

require "onebox"

url = ""
preview = Onebox.preview(url)
"#{preview}" == preview.to_s #=> true

Onebox has its own caching system but you can also provide (or turn off) your own system:

require "onebox"

url = ""
preview = Onebox.preview(url, cache: Rails.cache)
"#{preview}" == preview.to_s #=> true

In addition you can set your own options with this handy interface:

require "onebox"

Onebox.options = {
  cache: Rails.cache

url = ""
preview = Onebox.preview(url)
"#{preview}" == preview.to_s #=> true

Adding Support for a new URL

  1. Check if the site supports oEmbed or Open Graph. If it does, you can probably get away with just whitelisting the URL in Onebox::Engine::WhitelistedGenericOnebox. If the site does not support open standards, you can create a new engine.

  2. Create new onebox engine

``` ruby
# in lib/onebox/engine/name_onebox.rb

module Onebox
  module Engine
    class NameOnebox
      include LayoutSupport
      include HTML


      def data
          url: @url,
          name: raw.css("h1").inner_text,
          image: raw.css("#main-image").first["src"],
          description: raw.css("#postBodyPS").inner_text
  1. Create new onebox spec using FakeWeb
``` ruby
# in spec/lib/onebox/engine/name_spec.rb
require "spec_helper"

describe Onebox::Engine::NameOnebox do
  let(:link) { "" }
  let(:html) { }

  before do
    fake(link, response("name.response"))

  it "has the video's title" do
    expect(html).to include("title")

  it "has the video's still shot" do
    expect(html).to include("photo.jpg")

  it "has the video's description" do
    expect(html).to include("description")

  it "has the URL to the resource" do
    expect(html).to include(link)
  1. Create new mustache template
``` html
# in templates/name.mustache
<div class="onebox">
  <a href="{{url}}">
    <h2 class="host"></h2>
    <img src="{{image}}" />
  1. Create new fixture from HTML response for your FakeWeb request(s)
``` bash
curl --output spec/fixtures/oneboxname.response -L -X -GET
  1. Require in Engine module
``` ruby
# in lib/onebox/engine.rb
require_relative "engine/name_onebox"


Add this line to your application's Gemfile:

gem "onebox". "~> 1.2"

And then execute:

$ bundle

Or install it yourself as:

$ gem install onebox


  1. Fork it
  2. Create your feature branch (git checkout -b my-new-feature)
  3. Commit your changes (git commit -am 'Add some feature')
  4. Push to the branch (git push origin my-new-feature)
  5. Create new Pull Request
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