share to facebook with necessary information attached by default form.

share_to_facebook.erb

<% content_for :html_head_content do %>
  			<meta property="og:title" content="<%= @post.title %>"/>
        <meta property="og:type" content="website"/>
        <meta property="og:site_name" content="sample.com"/>
        <% if Rails.env == 'production' %>
        	<meta property="og:image" content="http://sample.com/assets/logo.png"/>
        <% else %>
        	<meta property="og:image" content="http://sample.com/logo.png"/>
        <% end %>
        <meta property="og:description" content="<%= strip_tags(@post.excerpt).strip[0, 200] %>"/>
        <!-- Twitter Card -->
        <meta name="twitter:card" content="summary">
        <meta name="twitter:site" content="@sample">
        <meta name="twitter:creator" content="@<%= @post.user.twitter %>">
        <meta name="twitter:url" content="http://www.sample.com<%= post_link(@post) %>">
        <meta name="twitter:title" content="<%= @post.title %>">
        <meta name="twitter:description" content="<%= strip_tags(@post.excerpt).strip[0, 200] %>">
        <% if @post.image? %>
	        <meta name="twitter:image" content="<%= @post.image %>">
        <% end %>
        <% unless Rails.env == 'production' %>
	        <script>
	        	var disqus_developer = 1; // developer mode is on
	        </script>
        <% end %>
<% end %>

<% content_for :javascripts do %>
  <script type= 'text/javascript'>
		$('.fb_share').live('click', function(event) {
			var width  = 575,
			    height = 400,
			    left   = ($(window).width()  - width)  / 2,
			    top    = ($(window).height() - height) / 2,
			    url    = this.href,
			    opts   = 'status=1' +
			             ',width='  + width  +
			             ',height=' + height +
			             ',top='    + top    +
			             ',left='   + left;

			window.open("http://www.facebook.com/sharer.php?u=<%= url_for(:action => params[:action], :controller => params[:controller], :only_path => false, :protocol => 'http') %>&t=<%= @post.title %>", 'Facebook', opts);

			return false;
		});
	</script>
<% end %>