node_access_example.module
<?php
// $Id: node_access_example.module,v 1.4 2005/03/29 01:27:26 JonBob Exp $
/**
* @file
* This is an example illustrating how to restrict access to nodes based on some
* criterion associated with the user.
*
* Database definition:
* @code
* DELETE FROM node_access;
* INSERT INTO node_access (nid, gid, realm, grant_view, grant_update,
* grant_delete) VALUES (0, 1, 'example', 1, 0, 0)
* @endcode
*
* This SQL needs to be run before the module will work properly. The installer
* system will probably perform this work in the future. The first line removes
* any existing grants, including (most importantly) the universal grant
* installed by default that gives read access to every node for everyone. The
* second line grants read access to every node for users with the "access
* private content" permission; in the scheme we're defining here, each node
* will either be private (in which case it can always be read by anyone with
* that permission) or public (in which case it can be read by everyone). We'll
* take care of public nodes in node_access_example_nodeapi().
*/
/**
* Implementation of hook_help().
*/
function node_access_example_help($section) {
switch ($section) {
case 'admin/modules#description':
return t('An example illustrating how to restrict access to nodes based on some criterion associated with the user.');
}
}
/**
* Implementation of hook_perm().
*
* In this example, we will use a simple permission to determine whether a user
* has access to "private" content. This permission is defined here.
*/
function node_access_example_perm() {
return array('access private content');
}
/**
* Implementation of hook_node_grants().
*
* Since we are restricting access based on a permission, we need to check that
* permission and return the appropriate result.
*
*/
function node_access_example_node_grants($account, $op) {
$grants = array();
if (user_access('access content', $account)) {
$grants[] = 0;
}
if (user_access('access private content', $account)) {
$grants[] = 1;
}
return array('example' => $grants);
}
/**
* Implementation of hook_nodeapi().
*
* Most of a node access module's work will be done via this hook. Several
* values of $op will require responses:
*
* - "form admin", "form pre", and/or "form post":
* The module will need to provide some mechanism for the access rights of a
* node to be managed. Some sort of form element on the node editing form is
* a typical means to accomplish this.
* - "delete", "insert", and "update":
* The module must take care of updating the node_access table appropriately
* when nodes are modified, probably using the form element mentioned above.
* Only the realm(s) handled by the module should be affected, so that multiple
* node access modules can peacefully coexist.
* - "validate":
* Depending on the user interface provided in the node form, the selection
* may need to be verified and validated here.
* - "settings":
* Modules may wish to provide default grants per node type using this hook.
*/
function node_access_example_nodeapi(&$node, $op, $arg = 0) {
switch ($op) {
case 'form admin':
// We present the selection for who can view the node in the administrative
// block, so users with the "administer nodes" permission can view and edit
// the settings.
if (!isset($node->access_example)) {
// Load the grants from the database.
$result = db_query('SELECT na.gid FROM {node_access} na WHERE na.nid = %d AND na.realm = \'example\' AND na.grant_view = 1', $node->nid);
$grant = db_fetch_object($result);
if ($grant && $grant->gid == 0) {
// The "public" grant was set.
$node->access_example = 0;
}
else {
$node->access_example = 1;
}
}
$output = form_checkbox(t('private'), 'access_example', 1, $node->access_example);
return $output;
case 'delete':
// When a node is deleted, delete any relevant grants.
db_query('DELETE FROM {node_access} WHERE nid = %d AND realm = \'example\'', $node->nid);
break;
case 'insert':
case 'update':
// Clear out any existing grants for the node, and set new ones.
db_query('DELETE FROM {node_access} WHERE nid = %d AND realm = \'example\'', $node->nid);
$node->access_example = isset($node->access_example) ? $node->access_example : 0;
if ($node->access_example == 0) {
// If the node is public, we need to grant access to everyone.
db_query('INSERT INTO {node_access} (nid, gid, realm, grant_view, grant_update, grant_delete) VALUES (%d, %d, \'example\', %d, %d, %d)', $node->nid, 0, 1, 0, 0);
}
break;
}
}
?>