Tags used for Cases, Activities or Attachments in Drupal Views?
On a development server, I edited sites/all/modules/civicrm/drupal/modules/views/components/civicrm.core.inc.

In the Tag section, I added:

$data['civicrm_tag']['table']['join']['civicrm_case'] = array(
    'left_table' =&gt; 'civicrm_entity_tag',
    'left_field' =&gt; 'tag_id',
    'field' =&gt; 'id',
  );


and

 $data['civicrm_entity_tag']['table']['join']['civicrm_case'] = array(
    // Directly links to tag table
    'left_field' =&gt; 'id',
    'field' =&gt; 'entity_id',
    'extra' =&gt; array(
      array(
        'field' =&gt; 'entity_table',
        'value' =&gt; 'civicrm_case',
        'numeric' =&gt; FALSE,
      ),
    ),
  );


After that, I was able to filter by case tags.

Would this have any unforeseen ramifications?  Does this cover all of my bases?

Would this be best put into a separate custom module?