menu_example.module

<?php


/**
 * @file
 * Demonstrates uses of the Menu APIs in Drupal, including hook_menu(),
 * hook_menu_alter(), and hook_menu_link_alter().
 */

/**
 * @defgroup menu_example Example: Menu API
 * @ingroup examples
 * @{
 * Examples using Menu API. (drupal 6)
 *
 * Demonstrates uses of the Menu APIs in Drupal, including hook_menu(),
 * hook_menu_alter(), and hook_menu_link_alter().
 *
 * This example is part of the Examples for Developers Project which you can download
 * and experiment with here: http://drupal.org/project/examples
 */

/**
 * Implementatation of hook_menu().
 */
function menu_example_menu() {
    // The simplest kind of menu: A simple call to a function with a menu entry.
    // The key of the menu item (menu_example/simplest) is the path that defines
    // the menu router entry.
    $items['menu_example'] = array(
        // The menu type is not required, as we're using the default.
        // 'type' => MENU_NORMAL_ITEM,
        // The title - do NOT use t() as t() is called automatically.
'title' => 'Menu Example',
        // Description (hover flyover for menu link). Does NOT use t(), which is
        // called automatically.
'description' => 'Simplest possible menu type, and the parent menu entry for others',
        // Function to be called when this path is accessed.
'page callback' => '_menu_example_basic_instructions',
        // Arguments to the page callback. Here's we'll use them just to provide
        // content for our page.
'page arguments' => array(
            t('This page is displayed by the simplest (and base) menu example. Note that the title of the page is the same as the link title. You can also <a href="!link">visit a similar page with no menu link</a>. Also, note that there is a hook_menu_alter() example that has changed the path of one of the menu items.', array(
                '!link' => url('menu_example/path_only'),
            )),
        ),
        // This is to be accessible to all users, so 'access callback' can be set
        // to TRUE, meaning that we should bypass all access checks.
'access callback' => TRUE,
        // If the page callback is located in another file, specify it here and
        // that file will be automatically loaded when needed.
        // 'file' => 'menu_example.module',
        // We can choose which menu gets the link. The default is 'navigation'.
        // 'menu_name' => 'navigation',
        // Show the menu link as expanded.
'expanded' => TRUE,
    );
    // Show a menu link in a menu other than the default "Navigation" menu.
    // The menu must already exist.
    $items['menu_example_alternate_menu'] = array(
        'title' => 'Menu Example: Menu in alternate menu',
        // Machine name of the menu in which the link should appear.
'menu_name' => 'primary-links',
        'page callback' => '_menu_example_menu_page',
        'page arguments' => array(
            t('This will be in the Primary Links menu instead of the default Navigation menu'),
        ),
        'access callback' => TRUE,
    );
    // A menu entry with simple permissions using user_access().
    // First, provide a courtesy menu item that mentions the existence of the
    // permissioned item.
    $items['menu_example/permissioned'] = array(
        'title' => 'Permissioned Example',
        'page callback' => '_menu_example_menu_page',
        'page arguments' => array(
            t('A menu item that requires the "access protected menu example" permission is at <a href="!link">menu_example/permissioned/controlled</a>', array(
                '!link' => url('menu_example/permissioned/controlled'),
            )),
        ),
        'access callback' => TRUE,
        'expanded' => TRUE,
    );
    // Now provide the actual permissioned menu item.
    $items['menu_example/permissioned/controlled'] = array(
        // The title - do NOT use t() as t() is called automatically.
'title' => 'Permissioned Menu Item',
        'description' => 'This menu entry will not show and the page will not be accessible without the "access protected menu example" permission.',
        'page callback' => '_menu_example_menu_page',
        'page arguments' => array(
            t('This menu entry will not show and the page will not be accessible without the "access protected menu example" permission.'),
        ),
        // For a permissioned menu entry, we provide an access callback which
        // determines whether the current user should have access. The default is
        // user_access(), which we'll use in this case. Since it's the default,
        // we don't even have to enter it.
        // 'access callback' => 'user_access',
        // The 'access arguments' are passed to the 'access callback' to help it
        // do its job. In the case of user_access(), we need to pass a permission
        // as the first argument.
'access arguments' => array(
            'access protected menu example',
        ),
        // The optional weight element tells how to order the submenu items.
        // Higher weights are "heavier", dropping to the bottom of the menu.
'weight' => 10,
    );
    // A menu router entry with no menu link. This could be used any time we
    // don't want the user to see a link in the menu. Otherwise, it's the same
    // as the "simplest" entry above. MENU_CALLBACK is used for all menu items
    // which don't need a visible menu link, including services and other pages
    // that may be linked to but are not intended to be accessed directly.
    // First, provide a courtesy link in the menu so people can find this.
    $items['menu_example/path_only'] = array(
        'title' => 'MENU_CALLBACK example',
        'page callback' => '_menu_example_menu_page',
        'page arguments' => array(
            t('A menu entry with no menu link (MENU_CALLBACK) is at <a href="!link">!link</a>', array(
                '!link' => url('menu_example/path_only/callback'),
            )),
        ),
        'access callback' => TRUE,
        'weight' => 20,
    );
    $items['menu_example/path_only/callback'] = array(
        // A type of MENU_CALLBACK means leave the path completely out of the menu
        // links.
'type' => MENU_CALLBACK,
        // The title is still used for the page title, even though it's not used
        // for the menu link text, since there's no menu link.
'title' => 'Callback Only',
        'page callback' => '_menu_example_menu_page',
        'page arguments' => array(
            t('The menu entry for this page is of type MENU_CALLBACK, so it provides only a path but not a link in the menu links, but it is the same in every other way to the simplest example.'),
        ),
        'access callback' => TRUE,
    );
    // A menu entry with tabs.
    // For tabs we need at least 3 things:
    // 1. A parent MENU_NORMAL_ITEM menu item (menu_example/tabs in this
    //    example.)
    // 2. A primary tab (the one that is active when we land on the base menu).
    //    This tab is of type MENU_DEFAULT_LOCAL_TASK.
    // 3. Some other menu entries for the other tabs, of type MENU_LOCAL_TASK.
    $items['menu_example/tabs'] = array(
        // 'type' => MENU_NORMAL_ITEM,  // Not necessary since this is the default.
'title' => 'Tabs',
        'description' => 'Shows how to create primary and secondary tabs',
        'page callback' => '_menu_example_menu_page',
        'page arguments' => array(
            t('This is the "tabs" menu entry.'),
        ),
        'access callback' => TRUE,
        'weight' => 30,
    );
    // For the default local task, we need very little configuration, as the
    // callback and other conditions are handled by the parent callback.
    $items['menu_example/tabs/default'] = array(
        'type' => MENU_DEFAULT_LOCAL_TASK,
        'title' => t('Default primary tab'),
        'weight' => 1,
    );
    // Now add the rest of the tab entries.
    foreach (array(
        t('second') => 2,
        t('third') => 3,
        t('fourth') => 4,
    ) as $tabname => $weight) {
        $items["menu_example/tabs/{$tabname}"] = array(
            'type' => MENU_LOCAL_TASK,
            'title' => $tabname,
            'page callback' => '_menu_example_menu_page',
            'page arguments' => array(
                t('This is the tab "@tabname" in the "basic tabs" example', array(
                    '@tabname' => $tabname,
                )),
            ),
            'access callback' => TRUE,
            // The weight property overrides the default alphabetic ordering of menu
            // entries, allowing us to get our tabs in the order we want.
'weight' => $weight,
        );
    }
    // Finally, we'll add secondary tabs to the default tab of the tabs entry.
    // The default local task needs very little information.
    $items['menu_example/tabs/default/first'] = array(
        'type' => MENU_DEFAULT_LOCAL_TASK,
        'title' => t('Default secondary tab'),
    );
    foreach (array(
        t('second'),
        t('third'),
    ) as $tabname) {
        $items["menu_example/tabs/default/{$tabname}"] = array(
            'type' => MENU_LOCAL_TASK,
            'title' => $tabname,
            'page callback' => '_menu_example_menu_page',
            'page arguments' => array(
                t('This is the secondary tab "@tabname" in the "basic tabs" example "default" tab', array(
                    '@tabname' => $tabname,
                )),
            ),
            'access callback' => TRUE,
        );
    }
    // All the portions of the URL after the base menu are passed to the page
    // callback as separate arguments, and can be captured by the page callback
    // in its argument list. Our _menu_example_menu_page() function captures
    // arguments in its function signature and can output them.
    $items['menu_example/use_url_arguments'] = array(
        'title' => 'Extra Arguments',
        'description' => 'The page callback can use the arguments provided after the path used as key',
        'page callback' => '_menu_example_menu_page',
        'page arguments' => array(
            t('This page demonstrates using arguments in the path (portions of the path after "menu_example/url_arguments". For example, access it with <a href="!link1">!link1</a> or <a href="!link2">!link2</a>).', array(
                '!link1' => url('menu_example/use_url_arguments/one/two'),
                '!link2' => url('menu_example/use_url_arguments/firstarg/secondarg'),
            )),
        ),
        'access callback' => TRUE,
        'weight' => 40,
    );
    // The menu title can be dynamically created by using the 'title callback'
    // which by default is t(). Here we provide a title callback which adjusts
    // the menu title based on the current user's username.
    $items['menu_example/title_callbacks'] = array(
        'title callback' => '_menu_example_simple_title_callback',
        'title arguments' => array(
            t('Dynamic title: username='),
        ),
        'description' => 'The title of this menu item is dynamically generated',
        'page callback' => '_menu_example_menu_page',
        'page arguments' => array(
            t('The menu title is dynamically changed by the title callback'),
        ),
        'access callback' => TRUE,
        'weight' => 50,
    );
    // Sometimes we need to capture a specific argument within the menu path,
    // as with the menu entry 'menu_example/placeholder_argument/3333/display',
    // where we need to capture the "3333". In that case, we use a placeholder in
    // the path provided in the menu entry. The (odd) way this is done is by using
    // array(numeric_position_value) as the value for 'page arguments'. The
    // numeric_position_value is the zero-based index of the portion of the URL
    // which should be passed to the 'page callback'.
    // First we provide a courtesy link with information on how to access
    // an item with a placeholder.
    $items['menu_example/placeholder_argument'] = array(
        'title' => 'Placeholder Arguments',
        'page callback' => '_menu_example_menu_page',
        'page arguments' => array(
            t('Demonstrate placeholders by visiting <a href="!link">menu_example/placeholder_argument/3343/display</a>', array(
                '!link' => url('menu_example/placeholder_argument/3343/display'),
            )),
        ),
        'access callback' => TRUE,
        'weight' => 60,
    );
    // Now the actual entry.
    $items['menu_example/placeholder_argument/%/display'] = array(
        'title' => 'Placeholder Arguments',
        'page callback' => '_menu_example_menu_page',
        // Pass the value of '%', which is zero-based argument 2, to the
        // 'page callback'. So if the URL is
        // 'menu_example/placeholder_argument/333/display' then the value 333
        // will be passed into the 'page callback'.
'page arguments' => array(
            2,
        ),
        'access callback' => TRUE,
    );
    // Drupal provides magic placeholder processing as well, so if the placeholder
    // is '%menu_example_arg_optional', the function
    // menu_example_arg_optional_load($arg) will be called to translate the path
    // argument to a more substantial object. $arg will be the value of the
    // placeholder. Then the return value of menu_example_id_load($arg) will be
    // passed to the 'page callback'.
    // In addition, if (in this case) menu_example_arg_optional_to_arg() exists,
    // then a menu link can be created using the results of that function as a
    // default for %menu_example_arg_optional.
    $items['menu_example/default_arg/%menu_example_arg_optional'] = array(
        'title' => 'Processed Placeholder Arguments',
        'page callback' => '_menu_example_menu_page',
        'page arguments' => array(
            2,
        ),
        // arg 2 (3rd arg) is the one we want.
'access callback' => TRUE,
        'weight' => 70,
    );
    $items['menu_example/menu_original_path'] = array(
        'title' => 'Menu path that will be altered by hook_menu_alter()',
        'page callback' => '_menu_example_menu_page',
        'page arguments' => array(
            t('This menu item was created strictly to allow the hook_menu_alter() function to have something to operate on. hook_menu defined the path as menu_example/menu_original_path. The hook_menu_alter() changes it to menu_example/menu_altered_path. You can try navigating to both paths and see what happens!'),
        ),
        'access callback' => TRUE,
        'weight' => 80,
    );
    return $items;
}

/**
 * Page callback for the simplest introduction menu entry.
 *
 * @param $content
 *   Some content passed in.
 */
function _menu_example_basic_instructions($content = NULL) {
    $base_content = t('This is the base page of the Menu Example. There are a number of examples
  here, from the most basic (like this one) to extravagant mappings of loaded
  placeholder arguments. Enjoy!');
    return '<div>' . $base_content . '</div><br /><div>' . $content . '</div>';
}

/**
 * Page callback for use with most of the menu entries. The arguments it
 * receives determine what it outputs.
 *
 * @param $content
 *   The base content to output.
 * @param $arg1
 *   First additional argument from the path used to access the menu
 * @param $arg2
 *   Second additional argument.
 */
function _menu_example_menu_page($content = NULL, $arg1 = NULL, $arg2 = NULL) {
    $output = '<div>' . $content . '</div>';
    if (!empty($arg1)) {
        $output .= '<div>' . t('Argument 1=%arg', array(
            '%arg' => $arg1,
        )) . '</div>';
    }
    if (!empty($arg2)) {
        $output .= '<div>' . t('Argument 2=%arg', array(
            '%arg' => $arg2,
        )) . '</div>';
    }
    return $output;
}

/**
 * Implements hook_perm() to provide a demonstration access string.
 */
function menu_example_perm() {
    return array(
        'access protected menu example',
    );
}

/**
 * Utility function to provide mappings from integers to some strings.
 * This would normally be some database lookup to get an object or array from
 * a key.
 *
 * @param $id
 *
 * @return
 *   The string to which the integer key mapped, or NULL if it did not map.
 */
function _menu_example_mappings($id) {
    $mapped_value = NULL;
    static $mappings = array(
        1 => 'one',
        2 => 'two',
        3 => 'three',
        99 => 'jackpot! default',
    );
    if (isset($mappings[$id])) {
        $mapped_value = $mappings[$id];
    }
    return $mapped_value;
}

/**
 * The special _load function to load menu_example.
 *
 * Given an integer $id, load the string that should be associated with it.
 * Normally this load function would return an array or object with more
 * information.
 *
 * @param $id
 *   The integer to load.
 *
 * @return
 *   A string loaded from the integer.
 */
function menu_example_id_load($id) {
    // Just map a magic value here. Normally this would load some more complex
    // object from the database or other context.
    $mapped_value = _menu_example_mappings($id);
    if (!empty($mapped_value)) {
        return t('Loaded value was %loaded', array(
            '%loaded' => $mapped_value,
        ));
    }
    else {
        return t('Sorry, the id %id was not found to be loaded', array(
            '%id' => $id,
        ));
    }
}

/**
 * Implements hook_menu_alter().
 *
 * Changes the path 'menu_example/menu_original_path' to 'menu_example/menu_altered_path'.
 * Changes the title callback of the 'user/UID' menu item.
 *
 * Remember that hook_menu_alter() only runs at menu_rebuild() time, not every
 * time the page is built, so this typically happens only at cache clear time.
 *
 * @param $items
 *   The complete list of menu router items ready to be written to the
 *   menu_router table.
 */
function menu_example_menu_alter(&$items) {
    // Change the path 'menu_example/menu_original_path' to 'menu_example/menu_altered_path'. This change will
    // prevent the page from appearing at the original path (since the item is being unset).
    // You will need to go to menu_example/menu_altered_path manually to see the page.
    if (!empty($items['menu_example/menu_original_path'])) {
        $items['menu_example/menu_altered_path'] = $items['menu_example/menu_original_path'];
        $items['menu_example/menu_altered_path']['title'] = 'Menu item altered by hook_menu_alter()';
        unset($items['menu_example/menu_original_path']);
    }
    // Here we will change the title callback to our own function, changing the
    // 'user' link from the traditional to always being "username's account".
    if (!empty($items['user/%user_uid_optional'])) {
        $items['user/%user_uid_optional']['title callback'] = 'menu_example_user_page_title';
    }
}

/**
 * Title callback to rewrite the '/user' menu link.
 *
 * @param $base_string
 *   string to be prepended to current user's name.
 */
function _menu_example_simple_title_callback($base_string) {
    global $user;
    $username = !empty($user->name) ? $user->name : t('anonymous');
    return $base_string . ' ' . $username;
}

/**
 * Title callback to rename the title dynamically.
 *
 * @param $account
 *   User account related to the visited page.
 */
function menu_example_user_page_title($account) {
    return t("@name's account", array(
        '@name' => $account->name,
    ));
}

/**
 * Implements hook_menu_link_alter().
 *
 * This code will get the chance to alter a menu link when it is being saved
 * in the menu interface at admin/build/menu. Whatever we do here overrides
 * anything the user/administrator might have been trying to do.
 *
 * @param $item
 *   The menu item being saved.
 * @param $menu
 *   The entire menu router table.
 */
function menu_example_menu_link_alter(&$item, $menu) {
    // Force the link title to remain 'Clear Cache' no matter what the admin
    // does with the web interface.
    if ($item['link_path'] == 'devel/cache/clear') {
        $item['link_title'] = 'Clear Cache';
    }
}

/**
 * Load an item based on its $id.
 *
 * In this case we're just creating a more extensive string. In a real example
 * we would load or create some type of object.
 *
 * @param $id
 */
function menu_example_arg_optional_load($id) {
    $mapped_value = _menu_example_mappings($id);
    if (!empty($mapped_value)) {
        return t('Loaded value was %loaded', array(
            '%loaded' => $mapped_value,
        ));
    }
    else {
        return t('Sorry, the id %id was not found to be loaded', array(
            '%id' => $id,
        ));
    }
}

/**
 * A to_arg() function is used to provide a default for the arg in the
 * wildcard. The purpose is to provide a menu link that will function if no
 * argument is given. For example, in the case of the menu item
 * 'menu_example/default_arg/%menu_example_arg_optional' the third argument
 * is required, and the menu system cannot make a menu link using this path
 * since it contains a placeholder. However, when the to_arg() function is
 * provided, the menu system will create a menu link pointing to the path
 * which would be created with the to_arg() function filling in the
 * %menu_example_arg_optional.
 *
 * @param $arg
 *   The arg (URL fragment) to be tested.
 */
function menu_example_arg_optional_to_arg($arg) {
    // If our argument is not provided, give a default of 99.
    return empty($arg) || $arg == '%' ? 99 : $arg;
}

/**
 * @} End of "defgroup menu_example".
 */