My hook_menu_alter() and page callback don't get triggered

Question

This question relates to How do I redirect a taxonomy menu item to another path?

I followed the recommendations of Clive and wrote a hook_menu_alter to provide my callback.

function material_menu_taxonomy_page_callback($term) {
  dsm('Entered material menu callback');
}

function material_menu_menu_alter () {
  $items['taxonomy/term/%taxonomy_term']['page callback'] = 'material_menu_taxonomy_page_callback'; 
}

I placed a code line dsm("Altering"); in the callback to see where in the process the callback is being called, but it never shows up.

I am fairly certain that I have the code correct.

• The hook has the name of the custom module.
• The callback name is correct.
• the callback is in the same file as the hook
• I have turned the module off and then on so that I can be sure that Drupal knows about mymodule_menu_alter
• And I have flushed the caches.

My assumption is that mymodule_menu_alter()' should change the callback in the menu item array and that the callback will be called each time the menu item is selected. That suggests that mydsm()` message should display at the top of the page requested by the menu.

While Clive's test indicated in his answer worked, my revisions did not. Following Clive's answer recommendations I revised the code as follows.

material.info file contained in modules subdirectory = sites/all/modules/Custom/material

name = Materials  
description = Redefine the path for materials menu
package = CR-Hub
core = 7.x
; Includes
files[] = material.module

material.module file in same subdirectory

function material_taxonomy_page_callback() {
  drupal_goto('taxonomy/term/1');
  // return 'Entered material menu callback';
}

function material_menu_alter(&$items) {
  // return 'Entered Material Menu Alter';
  $items['taxonomy/term/%taxonomy_term']['page callback'] = 'material_taxonomy_page_callback'; 
  return $items;
}

When I select any menu item neither drupal_goto(), or return 'any text' lines redirect the selected path from the menu item.

Answer 1

You haven't passed $items into the function ;)

function material_menu_menu_alter (&$items) {
  $items['taxonomy/term/%taxonomy_term']['page callback'] = 'material_menu_taxonomy_page_callback'; 
}

Without that you're not actually altering anything as $items doesn't exist in a global scope.

You'll also need to clear the caches again once you've made the change.

UPDATE

Working code that I've just verified:

material.info:

name = Materials  
description = Redefine the path for materials menu
package = CR-Hub
core = 7.x
; Includes
files[] = material.module

material.module

function material_taxonomy_page_callback($term) {
  // Calling drupal_goto() here will result in an infinite loop.
  // This is the page callback for pages with a URL like taxonomy/term/1 so
  // there's no need to redirect...you're already where you need to be.
  // This function is used to build up the new page content for the taxonomy page

  // As a test just output the name of the term related to this page.
  return $term->name;
}

function material_menu_alter (&$items) {
  $items['taxonomy/term/%taxonomy_term']['page callback'] = 'material_taxonomy_page_callback'; 

  // You don't need to return anything from this function as $items is passed in by reference...anything you change in that variable will be reflected in the $items var in the calling function.
}

Once installed if I go to any taxonomy page the content region contains just the name of the taxonomy term for that page (using return $term->name). If it's not working for you the only thing I can advise is to clear Drupal's caches, or check what custom/contributed modules you've got installed that might be overriding your code.

Answer 2

I think what you may be missing is that the taxonomy menu item has a file set to look for the callback in the taxonomy.pages.inc

Try this:

$items['taxonomy/term/%taxonomy_term']['page callback'] = 'your_callback';
$items['taxonomy/term/%taxonomy_term']['file'] = '';

Answer 3

I was trying to do exactly the same thing described in Clive's answer, but the override was not working.

Finally I found out that what was preventing it from working was that I had the module Taxonomy Display enabled on the site. Disabling it was the solution to my problem.

So, you should disable any views overriding taxonomy/term/% but you should also check your enabled modules!

Hope this helps.