Adding attributes to a tag using htmlpurifier

Question

I am trying to use HTMLPurifier to transform HTML by adding class attributes to paragraphs.

For example, for this input HTML:

<p>This is a paragraph</p>
<p>Another one</p>

This would be the output:

<p class="myclass">This is a paragraph</p>
<p class="myclass">Another one</p>

I read the doc and some forum post on that site but i could not figure it out how exactly I should do it?

Thanks in advance.

Answer 1

Here is a quick and dirty example that you can test on your own:

<?php

require_once 'lib/library/HTMLPurifier.auto.php';

class HTMLPurifier_AttrTransform_AnchorClass extends HTMLPurifier_AttrTransform
{
    public function transform($attr, $config, $context)
    {
      // keep predefined class
      if (isset($attr['class']))
      {
        $attr['class'] .= ' myclass';
      }
      else
      {
        $attr['class'] = 'myclass';
      }

      return $attr;
    }
}

$dirty_html = '<a href=""></a>
<a target="_blank" href=""></a>
<a href="" class="toto"></a>
<a href="" style="oops"></a>';

$config     = HTMLPurifier_Config::createDefault();
$htmlDef    = $config->getHTMLDefinition(true);

$anchor     = $htmlDef->addBlankElement('a');
$anchor->attr_transform_post[] = new HTMLPurifier_AttrTransform_AnchorClass();

$purifier   = new HTMLPurifier($config);

$clean_html = $purifier->purify($dirty_html);

var_dump($clean_html);
It outputs:

string '<a href="" class="myclass"></a>

<a href="" class="myclass"></a>

<a href="" class="toto myclass"></a>

<a href="" class="myclass"></a>' (length=135)