Add class to term-reference output

Question

I'm trying to add a simple class to a link outputted via print render($content['field_tags']). I'm using the Bootstrap theme. These are the approaches I've tried so far:

1. Hooking into template_preprocess_node - no luck here as the html isn't generated yet.
2. Hooking into template_field - this contains exactly what I expect but the links being generated don't obey the classes set here.
3. Hacking node.tpl.php and manually outputting the terms - this sort of works but it's not the best solution.

This is the output as it is at the moment:

<a href="/tags/drupal" typeof="skos:Concept" property="rdfs:label skos:prefLabel" datatype="">drupal</a>

I don't want to add any more modules as there has to be a code solution to this, I'm not sure what I'm missing here. How do I add a class to link outputted in field_tags?

Answer 1

One option would be to preprocess the field:

function MYTHEME_preprocess_field(&$vars) {
  if ($vars['element']['#field_name'] == 'field_tags') {
    array_walk($vars['items'], function(&$el) { $el['#options']['attributes']['class'][] = 'some-class'; } );
  }
}