template og tags binding

og.tpl

{% capture page_title %}{% if article %}{{ article.title }} — {{ page.site_title }}{% else %}{% if site.root_item.selected? %}{{ page.site_title }}{% else %}{{ page.title }} — {{ page.site_title }}{% endif %}{% endif %}{% endcapture %}

{% comment %}<!-- FACEBOOK OPENGRAPH -->{% endcomment %}
{% if site.data.fb_admin %}<meta property="fb:admins" content="{{ site.data.fb_admin }}">{% endif %}
<meta property="og:type" content="{% if article %}article{% else %}website{% endif %}">
<meta property="og:url" content="{{ site.url }}{% if article %}{{ article.url | remove_first:'/' }}{% else %}{{ page.url | remove_first:'/' }}{% endif %}">
<meta property="og:title" content="{{ page_title | escape }}">
<meta property="og:site_name" content="{{ page.site_title | escape }}">

{% if article %}
	{% if article.data.fb_image %}
		<meta property="og:image" content="{{ article.data.fb_image }}">
	{% elsif page.data.fb_image %}
		<meta property="og:image" content="{{ page.data.fb_image }}">
	{% elsif site.data.fb_image %}
		<meta property="og:image" content="{{ site.data.fb_image }}">
	{% endif %}
	<meta property="og:description" content="{{ article.excerpt | strip_html | truncate: 200 }}">
{% else %}
	{% if page.data.fb_image %}
		<meta property="og:image" content="{{ page.data.fb_image }}">
	{% elsif site.data.fb_image %}
		<meta property="og:image" content="{{ site.data.fb_image }}">
	{% endif %}
	{% unless page.description == nil or page.description == "" %}<meta property="og:description" content="{{ page.description }}">{% endunless %}
{% endif %}