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Html::serialize adds unwanted/duplicate xml:* attributes

Open on Drupal.org →
Created on 2 June 2021, over 3 years ago
Updated 6 November 2023, about 1 year ago
</code><h3 id="summary-problem-motivation">Problem/Motivation</h3>

The <code>\Drupal\Component\Utility\Html::serialize

method uses \DOMDocument::saveXML instead of \DOMDocument::saveHTML to turn a \DOMDocument object back into an HTML string. I know HTML is a form of XML, but in some cases this can cause issues.

For example: when the following piece of HTML is being passed to \Drupal\Component\Utility\Html::normalize (which calls the serialize method):

<p>The Dutch word for example is <span lang="nl">voorbeeld</span></p>

The output is:

<p>The Dutch word for example is <span lang="nl" xml:lang="nl">voorbeeld</span></p>

For some reason, a new xml:lang attribute was added.

Now that alone is not a real big problem. However, if at some point this output is being passed to Html::normalize again for a second time (for example two text filters that uses the Html::normalize), we get the following output:

<p>The Dutch word for example is <span lang="nl" xml:lang="nl" xml:lang="nl">voorbeeld</span></p>

You see that we now have the xml:lang twice which is faulty HTML. This looks like a bug in PHP or in libxml, but if we use saveHTML instead of saveXML, the problem is fixed (no xml:lang attributes are added.

The big question is: Why use the saveXML if there is a special saveHTML function available?

Steps to reproduce

The issue can easily be reproduced in the default Umami example profile:

  1. Install Drupal with the Umami profile
  2. Create a new basic page
  3. Fill the Body field with the following HTML:
    <p>The Dutch word for example is <span lang="nl">voorbeeld</span>.</p>
  4. Make sure the Basic HTML format is selected
  5. Save the page

Now, if you look in the source code of the page, you see the output is:
<p>The Dutch word for example is <span lang="nl" xml:lang="nl" xml:lang="nl">voorbeeld</span>.</p>

This is because in the Basic HTML format, multiple filters are enabled that use the Html::serialize method:

  • Align images
  • Caption images
  • Restrict images to this site
  • Track images uploaded via a Text Editor
  • Embed media

Proposed resolution

I think it is a better option to use \DOMDocument::saveHTML instead of \DOMDocument::saveXML in \Drupal\Component\Utility\Html::serialize.

I am not sure if the impact of this is a big problem.

Remaining tasks

  • Add tests

Release notes snippet

Edit Use \DOMDocument::saveHTML instead of \DOMDocument::saveXML in Html::serialize

🐛 Bug report
Status

Closed: outdated

Version

11.0 🔥

Component
Render  →

Last updated 3 days ago

Created by

🇳🇱Netherlands BryanDeNijs

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