hook_taxonomy_term_view_alter is not being called

Question

On my Drupal 7 site, I have a module which needs to determine the type of page being shown / being loaded.

I first implemented hook_entity_view_alter. Doing this:

/**
 * Implements hook_entity_view_alter
 */
/*
function rsc_search_entity_view_alter(&$build, $type)
{
  echo "$type <br/>";
  echo $build['#entity_type'].'<br/>';
}

shows the info I need, so I know that the hook is being called. BUT, on taxonomy term pages, nothing shows up, although there should be an entity with type 'taxonomy_term'. See the last few lines of code at: http://api.drupal.org/api/drupal/modules!taxonomy!taxonomy.module/function/taxonomy_term_view/7

So I tried the next thing, which is implementing hook_taxonomy_term_view_alter to catch those term pages:

/**
 * Implements hook_taxonomy_term_view_alter 
 */
function rsc_search_taxonomy_term_view_alter(&$build)
{
  $var = $build;
  $build['extra'] = array('#markup'=>'nothing');
  echo 'tax_term';
  if ($build['#view_mode']=='full')
  {
    echo '<pre>';
    var_dump($build);
    echo '</pre>';
  }
}

This, however, NEVER DOES ANYTHING!

As far as I understand the documentation, I * used the correct function names * used the correct function parameters * remembered to clear the caches

Any ideas on what went wrong? Why can't I implement taxonomy alteration hooks?

EDIT

Clive asked whether I am using views taxonomy. But I am using a custom taxonomy page, which still calls taxonomy_term_view

function CSL_custom_admin_menu_alter(&$items)
{
  $items['taxonomy/term/%taxonomy_term'] = array(
    'title' => 'Taxonomy term',
    'title callback' => 'taxonomy_term_title',
    'title arguments' => array(2),
    'page callback' => 'taxonomy_term_page',
    'page arguments' => array(2),
    'access arguments' => array('access content'),
    'file' => 'taxonomy.pages.inc',
    'file path' => 'sites/all/modules/CSL_custom_admin'
  );
}

Here is an extract from my taxonomy.pages.inc:

/**
 * Menu callback; displays all nodes associated with a term.
 *
 * @param $term
 *   The taxonomy term.
 * @return
 *   The page content.
 */
function taxonomy_term_page($term)
{
  drupal_set_breadcrumb(CSL_taxonomy_breadcrumb($term));

  drupal_add_feed('taxonomy/term/' . $term->tid . '/feed', 'RSS - ' . $term->name);

  $subs = CSL_taxonomy_subs_count(taxonomy_get_tree($term->vid, $term->tid, 1));

  $nids = CSL_taxonomy_nids($term->tid, TRUE, variable_get('default_nodes_main', 10), ( isset($term->field_enable_sort['und'][0]['value'])&&$term->field_enable_sort['und'][0]['value'] ) || ( isset($term->field_toelaat_sorteer['und'][0]['value'])&&$term->field_toelaat_sorteer['und'][0]['value'] ) );

  $build = array();

  // Add term heading if the term has a description
  if (!empty($term->description))
  {
    $build['term_heading'] = array(
        '#prefix' => '<div class="term-listing-heading">',
        '#suffix' => '</div>',
        'term' => taxonomy_term_view($term, 'full'),
        '#weight' => 1
    );
  }

  if ($nids && $subs)
  {
    $build['subterms'] = array
    (
        '#prefix' => '<div class="taxonomy-subterms-wrapper">',
        '#suffix' => '</div>',
        'subterms' => array
        (
            '#theme' => 'CSL_custom_admin_taxsubstable',
            '#rows' => $subs,
            '#weight' => 2
        )
    );

    $build['nodes'] = array
    (
        '#prefix' => '<div class="taxonomy-nodes-wrapper">',
        '#suffix' => '</div>',
        'nodes' => node_view_multiple(node_load_multiple($nids)),
        '#weight' => 3
    );
  }
  else if ($nids) // no subs
  {
    $build['subterms'] = array
    (
        '#prefix' => '<div class="taxonomy-subterms-wrapper">',
        '#suffix' => '</div>',
        '#markup' => '<strong>'.t('This term has no subcategories.').'</strong>',
        '#weight' => 2
    );

    $build['nodes'] = array
    (
        '#prefix' => '<div class="taxonomy-nodes-wrapper">',
        '#suffix' => '</div>',
        'nodes' => node_view_multiple(node_load_multiple($nids)),
        '#weight' => 3
    );
  }
  else if ($subs) // no nids
  {
    $build['subterms'] = array
    (
        '#prefix' => '<div class="taxonomy-subterms-wrapper">',
        '#suffix' => '</div>',
        'subterms' => array
        (
            '#theme' => 'CSL_custom_admin_taxsubstable',
            '#rows' => $subs
        ),
        '#weight' => 2
    );

    $build['nodes'] = array
    (
        '#prefix' => '<div class="taxonomy-nodes-wrapper">',
        '#suffix' => '</div>',
        '#markup' => '<strong>'.t('Refer to one of the subcategories for articles.').'</strong>',
        '#weight' => 3
    );
  }
  else // nothing to see
  {
    $build['nodes'] = array
    (
        '#prefix' => '<div class="taxonomy-nodes-wrapper">',
        '#suffix' => '</div>',
        '#markup' => '<strong>'.t('There is currently no content in this category.').'</strong>',
        '#weight' => 3
    );
  }

  $build['pager_top'] = array(
      '#theme' => 'pager',
      '#weight' => -5
  );

  $build['pager_bottom'] = array(
      '#theme' => 'pager',
      '#weight' => 5
  );

  return $build;
}

I know my module names should not start with a capital letter (CSL_), but that should not affect anything here.

Answer 1

It is a bug / missing feature in Drupal Core!

The taxonomy module does not exactly conform to standards... For example, where an $entity of type 'node' has the properties bundle and content, 'taxonomy_term' doesn't. Also, in core taxonomy, _view hooks are never called and _alter hooks are only called when the taxonomy term has a non-blank description field. There are some patches available in this discussion, but I wrote my own, because I override taxonomy.pages.inc in any case.

I see a lot of modules struggle with this, and it is still an arguing point for Drupal 8. http://drupal.org/search/apachesolr_search/hook_taxonomy_term_view

Thanks for pointing me in the right direction, Clive. I would otherwise not have looked at my taxonomy.pages.inc

An excerpt from my new custom taxonomy.pages.inc follows. I hope this helps someone!

function taxonomy_term_page($term)
{  
  // set breadcrumbs
  // add rss feeds
  // count subcategories and nodes

  $build = array();

  $view_mode = 'full';
  $langcode = $GLOBALS['language_content']->language;

  // NB Always call this, even if no description,
  // because other modules need hook_taxonomy_term_view_alter
  // and hook_entity_view_alter
  $term_renderarray = taxonomy_term_view($term, $view_mode, $langcode);

  // Add term heading if the term has a description
  if (!empty($term->description))
  {
    $build['term_heading'] = array(
        '#prefix' => '<div class="term-listing-heading">',
        '#suffix' => '</div>',
        'term' => $term_renderarray,
        '#weight' => 1
    );
  }

  // add stuff to $build['subterms'] and $build['nodes']

  $build['pager_top'] = array(
      '#theme' => 'pager',
      '#weight' => -5
  );

  $build['pager_bottom'] = array(
      '#theme' => 'pager',
      '#weight' => 5
  );

  // Keep modules that expect $entity->content to exist happy
  // otherwise this causes errors with implementations such as
  // field_conditional_state_entity_view()
  $term->content = $build;

  // Allow modules to make their own additions to the term.
  module_invoke_all('taxonomy_term_view', $term, $view_mode, $langcode);
  module_invoke_all('entity_view', $term, 'taxonomy_term', $view_mode, $langcode);

  return $build;
}

whew :)