Commit f163fa99 authored by Dries's avatar Dries

- Patch by JonBob: a significant documentation update for the menu system!
parent 1f288c11
......@@ -4,6 +4,60 @@
* @defgroup menu Menu system
* @{
* The Drupal menu system drives both the navigation system from a user
* perspective and the callback system that Drupal uses to respond to URLs
* passed from the browser. For this reason, a good understanding of the
* menu system is fundamental to the creation of complex modules.
* Drupal's menu system follows a simple hierarchy defined by paths.
* Implementations of hook_menu() define menu items and assign them to
* paths (which should be unique). The menu system aggregates these items
* and determines the menu hierarchy from the paths. For example, if the
* paths defined were a, a/b, e, a/b/c/d, f/g, and a/b/h, the menu system
* would form the structure:
* - a
* - a/b
* - a/b/c/d
* - a/b/h
* - e
* - f/g
* Note that the number of elements in the path does not necessarily
* determine the depth of the menu item in the tree.
* When responding to a page request, the menu system looks to see if the
* path requested by the browser is registered as a menu item with a
* callback. If not, the system searches up the menu tree for the most
* complete match with a callback it can find. If the path a/b/i is
* requested in the tree above, the callback for a/b would be used.
* The found callback function is called with any arguments specified in
* the "callback arguments" attribute of its menu item. After these
* arguments, any remaining components of the path are appended as further
* arguments. In this way, the callback for a/b above could respond to a
* request for a/b/i differently than a request for a/b/j.
* For an illustration of this process, see page_example.module.
* Access to the callback functions is also protected by the menu system.
* The "access" attribute of each menu item is checked as the search for a
* callback proceeds. If this attribute is TRUE, then access is granted; if
* FALSE, then access is denied. The first found "access" attribute
* determines the accessibility of the target. Menu items may omit this
* attribute to use the value provided by an ancestor item.
* In the default Drupal interface, you will notice many links rendered as
* tabs. These are known in the menu system as "local tasks", and they are
* rendered as tabs by default, though other presentations are possible.
* Local tasks function just as other menu items in most respects. It is
* convention that the names of these tasks should be short verbs if
* possible. In addition, a "default" local task should be provided for
* each set. When visiting a local task's parent menu item, the default
* local task will be rendered as if it is selected; this provides for a
* normal tab user experience. This default task is special in that it
* links not to its provided path, but to its parent item's path instead.
* The default task's path is only used to place it appropriately in the
* menu hierarchy.
......@@ -34,19 +88,21 @@
* Normal menu items show up in the menu tree and can be moved/hidden by
* the administrator.
* the administrator. Use this for most menu items. It is the default value if
* no menu item type is specified.
* Item groupings are used for pages like "node/add" that simply list
* subpages to visit.
* subpages to visit. They are distinguished from other pages in that they will
* disappear from the menu if no subpages exist.
* Callbacks simply register a path so that the correct function is fired
* when the URL is accessed.
* when the URL is accessed. They are not shown in the menu.
......@@ -57,20 +113,18 @@
* Modules may "suggest" menu items that the administrator may enable.
* Modules may "suggest" menu items that the administrator may enable. They act
* just as callbacks do until enabled, at which time they act like normal items.
* Local tasks are rendered as tabs by default.
* Local tasks are rendered as tabs by default. Use this for menu items that
* describe actions to be performed on their parent item. An example is the path
* "node/52/edit", which performs the "edit" task on "node/52".
* Local subtasks are rendered as a horizontal listing below the tabs by default.
* Every set of local tasks should provide one "default" task, that links to the
* same path as its parent when clicked.
......@@ -78,12 +132,14 @@
* Custom items are those defined by the administrator.
* Custom items are those defined by the administrator. Reserved for internal
* use; do not return from hook_menu() implementations.
* Custom menus are those defined by the administrator.
* Custom menus are those defined by the administrator. Reserved for internal
* use; do not return from hook_menu() implementations.
......@@ -688,20 +744,15 @@ function _menu_build() {
function _menu_item_is_accessible($mid) {
$menu = menu_get_menu();
if (array_key_exists('access', $menu['items'][$mid])) {
return $menu['items'][$mid]['access'];
// Follow the path up to find the actual callback.
// Follow the path up to find the first "access" attribute.
$path = $menu['items'][$mid]['path'];
while ($path && (!array_key_exists($path, $menu['path index']) || !array_key_exists('callback', $menu['items'][$menu['path index'][$path]]))) {
while ($path && (!array_key_exists($path, $menu['path index']) || !array_key_exists('access', $menu['items'][$menu['path index'][$path]]))) {
$path = substr($path, 0, strrpos($path, '/'));
if (empty($path)) {
return FALSE;
$callback_mid = $menu['path index'][$path];
return $menu['items'][$callback_mid]['access'];
return $menu['items'][$menu['path index'][$path]]['access'];
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