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Facebook open graph tags in Apostrophe

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Facebook open graph tags can improve the way your pages appear when shared on Facebook, provided you use them correctly. The most frequently requested tag is og:image, followed by og:title, og:description and og:type. Often you can get away with just setting og:image. We'll look at how to do that.

However, any URLs you do set must be absolute URLs.

Absolute URLs in Apostrophe

For reasons unknown to the rest of the Internet, Facebook has never implemented support for parsing relative URLs, even if they start with a /. They consider it an error. Why? Who knows.

On 2016-04-04 we made it easier to get absolute URLs by implementing a straightforward absoluteUrls option for use in app.js:

var site = require('apostrophe-site')({
  // Other options, then...
  hostName: '',
  absoluteUrls: true,
  // Then other options...

The hostName option sets the hostname of the production site, and the absoluteUrls option indicates that page.url, snippet.url, the URLs of images in slideshows, etc. should always be absolute URLs pointing to the hostName that you configured.

What about secure sites?

hostName isn't enough information to figure out if the site requires https. Here's an alternative:

var site = require('apostrophe-site')({
  // Other options, then...
  hostName: '',
  baseUrl: '',
  absoluteUrls: true,
  // Then other options...

But what about URLs in development?

This is great, but you don't want your development URLs to point at your production server.

So use a data/local.js file on your production server. Everything here is merged with the object you pass to apostrophe-site in app.js. And data/local.js is never deployed. You set it up directly on the server. So you can set absoluteUrls differently in production. For instance, here's a typical production data/local.js file:

  // minify css and js files in production
  minify: true,
  // production hostname and baseUrl
  hostName: '',
  baseUrl: '',
  // absolute URLs in production
  absoluteUrls: true

You typically don't want to turn on absoluteUrls in your development environment.

Great, I have absolute URLs. How do I generate my og:meta tags?

It's pretty easy, since page.url is now absolute, and so are your image URLs. Here's a classy example:

{% set firstImage = aposAreaImage(page, 'thumbnail') or aposAreaImage(page, 'body') %}
{% set fbImage = aposAreaImage(page, 'facebookImage') %}
{% set description = aposAreaPlaintext(page, 'body', {}) %}
{% block extraHead %}
  {% if fbImage %}
    <meta property="og:image" content="{{ aposFilePath(fbImage, { size: 'full' }) }}" />
  {% elif firstImage %}
    <meta property="og:image" content="{{ aposFilePath(firstImage, { size: 'full' }) }}" />
  {% endif %}
  {% if description %}
  <meta name="description" property="og:description" content="{{description | truncate(200) | e }}" />
  {% endif %}
  <meta property="og:url" content="{{page.url}}">
  <meta property="og:title" content="{{page.title}}">
{% endblock %}

If there is a singleton named facebookImage, we use that for og:url. If not we use the first image we find in the thumbnail or body areas. This allows for custom Facebook images, if you want to include them in your page or snippet schema, and also allows for Apostrophe to track something down to use instead.

aposFilePath takes an image object and generates a path to it. We take care to specify the size we want. full is a good choice. Facebook will reject large originals.

You could choose to have a Facebook-specific description field in your schema as well. The code here pulls plaintext from the body area for that purpose.

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