Fb Graph Gem for Rails : How to Post dynamic contents to Facebook Wall from your Rails Application

This post will introduce the usage of fb_graph Gem with your existing Rails Application.fb_graph has already done a lot for you guys to exploit the FB API features with your Rails Application , you can have an eye on this fb_graph Gem before going through this post.

Suppose you have a blogger kind of application, and when you compose a new post , you would like to share the same in your Facebook wall, and also would like to give the same option for all the users ,those who liked your post and would like to share the same in their Facebook Wall.

I think now almost all the websites are using this feature to increase their user traffic , to popularize their sites,  Since Facebook turned out to be a great option for advertising and marketing your site content.

One day i also felt the same and after one complete days of effort ..... i was successful.            I thought i should share the same for you guys to reduce your one days effort ( or may be less ) for implementing this FB share option.

I hope i am not boring you , anyway stop to all kind of rubbish introduction and lets start coding ..

As usual first of all add fb_graph Gem to your Gemfile

gem 'fb_graph'

After that we have to create 2 actions for authenticating the User to Facebook and After authenticating the user we need a Callback action and this will share the Contents to that particular Users Facebook Wall.

Here we start from the Route file , mention your roots and controller actions here.

route file

 match "/fb_share/auth" => "fb_share#auth"  , :method => :get , :as => :fb_auth

 match "/fb_share/callback" => "fb_share#callback"  , :method => :get , :as => :fb_callback

Before get in to the serious part , i would like to tell you more about How i implemented this or what was my requirement.

Like i said before , suppose we have a blogger application , we are going to display the FB share button just below each post.

Requirements

•  When user clicks on the share button, it should redirect the user to Facebook login, and after allowing the permission to post , The content should post on the Users FB Wall.
• Contents should be,
• Title of my Blogpost.
• Title should be a link to my Blog Posts detail page. 
• Small Descrition.
• Thumbnail Image (If you want ).

Steps

• When User clicks on share button, We should call an action and here that probably be an Auth Action.
• But after authorizing the user , Facebook will redirect the user back to our Applications Callback action . So at that time , from where will we able to get the Contents like (Title , Description , URL, Image path) ?
• For that reason , i just implemented a cookie for storing all these information .
• When User Clicks on share button , We will pass all these information to Auth action.We Will Assign all these details to Each cookie.
• After Authenticating the User with (Key , Secret) pair, Facebook will redirect the user back to the Callback Action with Authorization code.
• Then we will call the feed action provided by the FB gem and will assign all these contents like ( Title, Description , image path & URL) from the cookie .
• The Rest of the things you dont need to care about . FB Gem will do it for you.

FBShare Controller Actions

class FbShareController < ApplicationController


  def auth

     cookies["title"] = { :value => "#{params[:title]}", :expires => 1.minute.from_now }
     cookies["url"] = { :value => "#{params[:url]}", :expires => 1.minute.from_now }
     cookies["desc"] = { :value => "#{params[:desc]}", :expires => 1.minute.from_now }

   

  @client = client

    redirect_to @client.authorization_uri(
      :scope => [ :offline_access , :publish_stream]
    )

  end


  def callback

    @client = client
    @client.authorization_code = params[:code]

    access_token = @client.access_token! :client_auth_body # => Rack::OAuth2::AccessToken

    me = FbGraph::User.me(access_token)

    title = cookies["title"]
    url = cookies["url"]
    desc  = cookies["desc"]

    me.feed!(

        :message =>  title ,
        :picture => / Your Image path / ,
        :link => url,
        :name => title,
        :description => desc
    )

    redirect_to root_path ( You Application Action path After sharing the content to FB)

  end


  private


  def client

    key = "APP KEY"
    secret = "SECRET KEY"
    fb_auth = FbGraph::Auth.new(key, secret)
    client = fb_auth.client
    client.redirect_uri = "http://#{request.host_with_port}/fb_share/callback"

    client

  end

end

Checkout my Twitter & Linkedin Share posts also ...