How do I access the page arguments? - php

Question

I am building a custom module in Drupal 7. I have a URL which is like "review/edit/2"; I want that number in the end of the URL.
How can I access it using hook_menu()? A small snippet would be good.

Answer 1

This is a very simple example that will pass everything after review/edit/ to your page callback function:
function mymodule_menu() {
$items['review/edit/%'] = array(
'title' => 'Title',
'page callback' => 'mymodule_page_callback',
'page arguments' => array(2),
'access arguments' => array('access administration pages')
);
return $items;
}
function mymodule_page_callback($arg) {
// For the URL review/edit/2, $arg is equal to 2
}

Answer 2

The question is effectively two questions:
How do I access page arguments that are passed through the URL?
How do I create a menu that is used for more than one URL?
The answer for the first question is that every number that is used to define the page arguments of a menu callback (this is valid also for the access arguments, the title arguments, and the theme arguments) is replaced from the equivalent part of the path.
For example, a module can implement hook_menu() using the following code (the example is used in the documentation for hook_menu()):
function mymodule_menu() {
$items['abc/def'] = array(
'page callback' => 'mymodule_abc_view',
'page arguments' => array(1, 'foo'),
);
return $items;
}
When users access example.com/abc/def, the arguments passed to the page callback are "abc" and "foo". If I wanted to pass 1 to the page callback, I would have to define the menu callback as following:
function mymodule_menu() {
$items['abc/def'] = array(
'page callback' => 'mymodule_abc_view',
'page arguments' => array('1', 'foo'),
);
return $items;
}
In this case, the arguments passed to the page callback are "1" and "foo" because only the numbers used in the argument array are replaced. (It doesn't include strings that can be casted to numbers.)
The answer to the second question is to use wildcards to define the menu callback, which are of two types: the generic %, or the wildcard associated with an autoloader function (e.g. %node, %user).
Using wildcards, I can define a menu callback associated with a path such as "test/event/%" that will match more than one URL, such as example.com/test/event/string example.com/test/event/234q3, or example.com/test/event/369014, where the % character is replaced with any string made of all the characters until the first slash.
Using a wildcard such as %node, the value matched from the wildcard is passed to a function (in this case, node_load()), and the value returned from that value is passed to the page callback.
As your menu callback replies to a path starting with "review/edit," I get that the last number is the node ID of a review node that needs to be edit; in such case, I would implement hook_menu() using the following code:
function mymodule_menu() {
$items['review/edit/%node'] = array(
'page callback' => 'mymodule_review_edit',
'page arguments' => array(2),
);
return $items;
}
function mymodule_review_edit($node) {
// $node contains the node object for the node ID passed in the URL.
}
There is a difference between using the generic wildcard, and using a more specific wildcard: When the auto-loader function returns FALSE, the user gets a "page not found" error. This is useful to filter out the wrong arguments. For example, if I would call the menu callback I previously defined with example.com/review/edit/fersgdsf, I would get a "page not found" error because node_load() would not find a node with ID equal to "fersgdsf" (node IDs are numbers, not strings). I would not need to first verify that the argument is an integer, because node_load() will return FALSE when it doesn't find a node with the passed ID, which happens when I pass a string that isn't equal to a number.
Drupal 6 and higher defines other wildcards, such as %user, _%taxonomy_vocabulary_; the list for Drupal 6 is reported at the bottom of Wildcard usage and core's wildcards, which also explain how to use wildcards. That documentation page is for Drupal 6, but it is still valid for Drupal 7; as far as I know, Drupal 7 doesn't define new wildcards.