discourse/README.md

onebox
----------

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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](http://discourse.org) but has since been
extracted into this convenient gem for all to use!

Usage
=====

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

``` ruby
require "onebox"
```

Then pass a link to the library's interface:

``` ruby
require "onebox"

url = "http://www.amazon.com/gp/product/B005T3GRNW/ref=s9_simh_gw_p147_d0_i2"
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:

``` ruby
require "onebox"

url = "http://www.amazon.com/gp/product/B005T3GRNW/ref=s9_simh_gw_p147_d0_i2"
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:

``` ruby
require "onebox"

url = "http://www.amazon.com/gp/product/B005T3GRNW/ref=s9_simh_gw_p147_d0_i2"
preview = Onebox.preview(url, cache: Rails.cache)
"#{preview}" == preview.to_s #=> true
```

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

``` ruby
require "onebox"

Onebox.options = {
  cache: Rails.cache
}

url = "http://www.amazon.com/gp/product/B005T3GRNW/ref=s9_simh_gw_p147_d0_i2"
preview = Onebox.preview(url)
"#{preview}" == preview.to_s #=> true
```

Development Preview Interface
=============================

The onebox gem comes with a development server for previewing the results
of your changes. You can run it by running `rake server` after checking
out the project. You can then try out URLs.

The server doesn't reload code changes automatically (PRs accepted!) so
make sure to hit CTRL-C and restart the server to try a code change out.


Adding Support for a new URL
============================

  1. Check if the site supports [oEmbed](http://oembed.com/) or [Open Graph](https://developers.facebook.com/docs/opengraph/).
     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

          private

          def data
            {
              url: @url,
              name: raw.css("h1").inner_text,
              image: raw.css("#main-image").first["src"],
              description: raw.css("#postBodyPS").inner_text
            }
          end
        end
      end
    end
    ```

  3. Create new onebox spec using [FakeWeb](https://github.com/chrisk/fakeweb)

    ``` ruby
    # in spec/lib/onebox/engine/name_spec.rb
    require "spec_helper"

    describe Onebox::Engine::NameOnebox do
      let(:link) { "http://example.com" }
      let(:html) { described_class.new(link).to_html }

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

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

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

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

      it "has the URL to the resource" do
        expect(html).to include(link)
      end
    end
    ```

  4. Create new mustache template

    ``` html
    # in templates/name.mustache
    <div class="onebox">
      <a href="{{url}}">
        <h1>{{name}}</h1>
        <h2 class="host">example.com</h2>
        <img src="{{image}}" />
        <p>{{description}}</p>
      </a>
    </div>
    ```

  5. Create new fixture from HTML response for your FakeWeb request(s)

    ``` bash
    curl --output spec/fixtures/oneboxname.response -L -X -GET http://example.com
    ```

  6. Require in Engine module

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


Installing
==========

Add this line to your application's Gemfile:

    gem "onebox", "~> 1.2"

And then execute:

    $ bundle

Or install it yourself as:

    $ gem install onebox


Contributing
============

  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