How to switch between conflictual hooks?

Question

In a custom module I'm implementing the hook_menu_alter hook to alter the page callback for the $menu['taxonomy/term/%taxonomy_term'] menu.

I've noticed that my hook is not implemented because another contrib module ( Taxonomy Display module ) already implements the same hook (all works fine if I disable TD).

What I need is not to prevail on TD hook with mine, but to use my hook under a certain condition, and TD hook for all other cases.

The condition is the presence of parameter "v" in the querystring, like the following example:

if url == taxonomy/term/tid?v=value then use mymodule_menu_alter

if url == taxonomy/term/tid then use taxonomy_display_menu_alter

How I can do that?

Thank you very much!

MXT

Answer 1

If you implement a hook, it will always be executed.

The condition of a query string makes things more complicated in your situation, because all menu items are defined by their path (taxonomy/term/tid in your case). This means that - as far as Drupal is concerned - taxonomy/term/tid?v=value and taxonomy/term/tid have the same menu item, so both requests will be handled by the same code.

Is it really necessary that the URL takes the form of ?v=value? If you could make it taxonomy/term/tid/value, you can create your own custom menu item for taxonomy/term/%/%, and simply leave the taxonomy/term/tid path as is.

Answer 2

I'm not sure but perhaps you should make the weight of your module higher than Taxonomy Displays, so your modules hook get called first. Check out this http://drupal.org/node/110238

Answer 3

I've reached a working solution:

function mymodule_module_implements_alter(&$implementations, $hook) {
  if ($hook == 'menu_alter') {
    // move mymodule at the end of the list, so it will be implemented at last: 
    $group = $implementations['mymodule'];
    unset($implementations['mymodule']);
    $implementations['mymodule'] = $group;
  }
}

function mymodule_menu_alter(&$menu) {
  if (isset($menu['taxonomy/term/%taxonomy_term'])) {
    // alter menu to serve my own custom term page
    $menu['taxonomy/term/%taxonomy_term']['page callback'] = 'mymodule_term_page';
  }
}

function mymodule_term_page($term) {

    $params = drupal_get_query_parameters();
    $vocab = taxonomy_vocabulary_load($term->vid);

    // If this voc hasn't to be processed, return the default taxonomy term page:
    if(!variable_get('mymodule_' . $vocab->machine_name . '_enabled')) {
      module_load_include('inc', 'taxonomy', 'taxonomy.pages');
      return taxonomy_term_page($term);
    }

    // If param 'v' is present in querystring
    if(isset($params['v'])) {
      // return another custom callback term page:
      return mymodule_show_term_tree($term);
    }
    else {
      // Else call Taxonomy Display module calback page:
      module_load_include('module', 'taxonomy_display');
      return taxonomy_display_taxonomy_term_page($term);
    }
}

I'll hope this will be usefull to others.