UPDATE 2021/12/04: Updated XPath query to reflect recent changes on what is returned by Twitter.
UPDATE 2021/11/11: Updated XPath query to handle threaded tweets.

Twitter is one of my primary sources of content to read, the other being RSS feeds.

But unlike the RSS feeds, when I submit a twitter link to a wallabag instance it will only fetch the tweet. Then I will need to do an extra action to fetch the article that was originally in this tweet.

We'll take the following tweet for the illustration:

It would be perfect if wallabag was able to directly fetch the linked article.

Well… The good news is it's quite simple to achieve that.

Behind the scene wallabag uses site-config files to apply advanced instructions to extract content.

As an example, here are some instructions for twitter.com:

title: //title
body: (//p[contains(@class, 'js-tweet-text')])[1]
author: (//strong[contains(@class, 'fullname')])[1]
http_header(User-Agent): Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)

These instructions basically say to find title, body and author according to these specific XPath queries. The last line says to set the specified value for the header User-Agent before sending the request.

Among all supported instructions there is one that lets you instruct the fetching tool to eventually fetch a link that can be found in the fetched content. This instruction is single_page_link and was originally added for articles that spawn over several pages but provide a link for fetching the whole content at once.

Here was the DOM tree of a tweet page returned by Twitter before a recent change1:

<!-- [clipped] -->
<div class="tweet permalink-tweet js-actionable-user js-actionable-tweet js-original-tweet has-cards no-replies js-initial-focus focus" data-associated-tweet-id="1394723094183428101" data-tweet-id="1394723094183428101" data-item-id="1394723094183428101" data-permalink-path="/Kdecherf/status/1394723094183428101" data-conversation-id="1394723094183428101" data-tweet-nonce="1394723094183428101-041d44f2-9198-4194-86c2-cabb9c6526d4" data-tweet-stat-initialized="true" data-screen-name="Kdecherf" data-name="Kevin Decherf" data-user-id="21924424" data-you-follow="false" data-follows-you="false" data-you-block="false" data-reply-to-users-json="[{&quot;id_str&quot;:&quot;21924424&quot;,&quot;screen_name&quot;:&quot;Kdecherf&quot;,&quot;name&quot;:&quot;Kevin Decherf&quot;,&quot;emojified_name&quot;:{&quot;text&quot;:&quot;Kevin Decherf&quot;,&quot;emojified_text_as_html&quot;:&quot;Kevin Decherf&quot;}}]" data-disclosure-type="" data-card2-type="summary" data-has-cards="true" tabindex="0">
   <div class="content clearfix">
   <!-- [clipped] -->

   <div class="js-tweet-text-container">
      <p class="TweetTextSize TweetTextSize--jumbo js-tweet-text tweet-text" data-aria-label-part="0" lang="en">
         New post: 'Reclaim disk from Ignite and Firecracker'
         <a href="https://t.co/oR2XfX7LV3" rel="nofollow noopener" dir="ltr" data-expanded-url="https://kdecherf.com/blog/2021/05/18/reclaim-disk-from-ignite-and-firecracker/" target="_blank" title="https://kdecherf.com/blog/2021/05/18/reclaim-disk-from-ignite-and-firecracker/" class="twitter-timeline-link"><span class="tco-ellipsis"></span><span class="invisible">https://</span><span class="js-display-url">kdecherf.com/blog/2021/05/1</span><span class="invisible">8/reclaim-disk-from-ignite-and-firecracker/</span><span class="tco-ellipsis"><span class="invisible">&nbsp;</span></span></a>
   <!-- [clipped] -->

We can see that even if Twitter overrides the href property with their url shortener, the actual link is available in the data-expanded-url property.2

Then we could use the following XPath query to extract the link we want:

//meta[@itemprop='mainEntityOfPage']/parent::div//article//a[contains(@rel, 'noreferrer') and contains(@href, 'https://t.co')]/@href

Now that we have the XPath query we can use it with a single_page_link instruction to order wallabag to follow any link it would find in a tweet page. For that we need to add the following line to the file vendor/j0k3r/graby-site-config/twitter.com.txt:

single_page_link: //meta[@itemprop='mainEntityOfPage']/parent::div//article//a[contains(@rel, 'noreferrer') and contains(@href, 'https://t.co')]/@href

With this modification, sending the link https://twitter.com/Kdecherf/status/1394723094183428101 to wallabag will now fetch https://kdecherf.com/blog/2021/05/18/reclaim-disk-from-ignite-and-firecracker/; which is the link that can be found in the tweet.

Why not pushing this change to upstream?

I could have proposed this change to the repository used by wallabag and other applications. However this new behavior may not be what users want as the default, like for Reddit.

Further reading

  1. Without specifying the User-Agent of Googlebot, Twitter sends a client-side rendered page with javascript, see https://github.com/fivefilters/ftr-site-config/pull/837 ↩︎

  2. Twitter recently changed the way they show tweets, the attribute data-expanded-url is no longer available and the DOM tree is clogged with a lot of crap. ↩︎