node_access_example.module
<?php
// $Id: node_access_example.module,v 1.18 2009/10/13 21:21:52 salvis Exp $
/**
* @file
* This is an example illustrating how to restrict access to nodes based on
* some criterion associated with the user.
*
* This example module will simply set a single flag on a node: 'private'. If
* the flag is set, only users with the 'view private content' flag can see
* the node, and all users with 'edit private content' can edit (but not
* delete) the node.
*
* Additionally we will ensure that the node author can always view, edit,
* and delete the node by providing an additional access realm that grants
* privileges to the node's author.
*
*/
/**
* Implementation of hook_permission().
*
* 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_permission() {
return array(
'access private content' => array(
'title' => t('Access private content'),
'description' => t('May view posts that are marked private.'),
),
'edit private content' => array(
'title' => t('Edit private content'),
'description' => t('May edit posts that are marked private.'),
),
);
}
/**
* Implementation of hook_node_grants().
*
* Tell the node access system what GIDs the user belongs to for each realm.
* In this example, we are providing two realms: the example realm, which
* has just one group id (1) and the user is either a member or not depending
* upon the operation and the access permission set.
*
* We are also setting up a realm for the node author, though, to give it
* special privileges. That has 1 GID for every UID, and each user is
* automatically a member of the group where GID == UID.
*
*/
function node_access_example_node_grants($account, $op) {
if ($op == 'view' && user_access('access private content', $account)) {
$grants['example'] = array(1);
}
if (($op == 'update' || $op == 'delete') && user_access('edit private content', $account)) {
$grants['example'] = array(1);
}
$grants['example_author'] = array($account->uid);
return $grants;
}
/**
* Implementation of hook_node_access_records().
*
* All node access modules must implement this hook. If the module is
* interested in the privacy of the node passed in, return a list of
* node access values for each realm and grant ID we offer.
*/
function node_access_example_node_access_records($node) {
// We only care about the node if it's been marked private. If not, it is
// treated just like any other node and we completely ignore it.
if (!empty($node->private)) {
$grants = array();
$grants[] = array(
'realm' => 'example',
'gid' => 1,
'grant_view' => 1,
'grant_update' => 1,
'grant_delete' => 0,
'priority' => 0,
);
// For the example_author array, the GID is equivalent to a UID, which
// means there are many many groups of just 1 user.
$grants[] = array(
'realm' => 'example_author',
'gid' => $node->uid,
'grant_view' => 1,
'grant_update' => 1,
'grant_delete' => 1,
'priority' => 0,
);
return $grants;
}
}
/**
* Implementation of hook_form_alter()
*
* This module adds a simple checkbox to the node form labeled private. If the
* checkbox is checked, only the node author and users with 'access private content'
* privileges may see it.
*/
function node_access_example_form_alter(&$form, &$form_state, $form_id) {
if ($form['#id'] == 'node-form') {
$form['private'] = array(
'#type' => 'checkbox',
'#title' => t('Private'),
'#description' => t('Check here if this content should be set private and only shown to privileged users.'),
'#default_value' => isset($form['#node']->private) ? $form['#node']->private : FALSE,
);
}
}
/**
* Implementation of hook_node_load().
*/
function node_access_example_node_load($nodes, $types) {
$result = db_query('SELECT nid, private FROM {node_access_example} WHERE nid IN (:nids)', array(':nids' => array_keys($nodes)));
foreach ($result as $record) {
$nodes[$record->nid]->private = $record->private;
}
}
/**
* Implementation of hook_node_delete().
*
* The module must track the access status of the node.
*/
function node_access_example_node_delete($node) {
db_delete('node_access_example')->condition('nid', $node->nid)->execute();
}
/**
* Implementation of hook_node_insert().
*
* The module must track the access status of the node.
*/
function node_access_example_node_insert($node) {
if (isset($node->private)) {
db_insert('node_access_example')->fields(array('nid' => $node->nid, 'private' => (int)$node->private))->execute();
}
}
/**
* Implementation of hook_node_update().
*
* The module must track the access status of the node.
*/
function node_access_example_node_update($node) {
db_query('UPDATE {node_access_example} SET private = %d WHERE nid = %d', $node->private, $node->nid);
}
/**
* Implementation of hook_node_access_explain().
*
* hook_node_access_explain() is defined in devel_node_access.module, which
* will help you and your users to figure out how node access works.
*
* The explanations are purposely not translatable to allow getting support on
* drupal.org.
*/
function node_access_example_node_access_explain($row) {
switch ($row->realm) {
case 'example':
return array('Users with <i>access private content</i> (<i>' . (user_access('access private content')? 'yes' : 'no') . '</i>) may view and users with <i>edit private content</i> (<i>' . (user_access('edit private content')? 'yes' : 'no') . '</i>) may edit this node.');
break;
case 'example_author':
return array("Full access for the author, user <i>$row->gid</i>.");
break;
}
}