function hook_node_grants

Inform the node access system what permissions the user has.

This hook is for implementation by node access modules. In this hook, the module grants a user different "grant IDs" within one or more "realms". In hook_node_access_records(), the realms and grant IDs are associated with permission to view, edit, and delete individual nodes.

The realms and grant IDs can be arbitrarily defined by your node access module; it is common to use role IDs as grant IDs, but that is not required. Your module could instead maintain its own list of users, where each list has an ID. In that case, the return value of this hook would be an array of the list IDs that this user is a member of.

A node access module may implement as many realms as necessary to properly define the access privileges for the nodes. Note that the system makes no distinction between published and unpublished nodes. It is the module's responsibility to provide appropriate realms to limit access to unpublished content.

Node access records are stored in the {node_access} table and define which grants are required to access a node. There is a special case for the view operation -- a record with node ID 0 corresponds to a "view all" grant for the realm and grant ID of that record. If there are no node access modules enabled, the core node module adds a node ID 0 record for realm 'all'. Node access modules can also grant "view all" permission on their custom realms; for example, a module could create a record in {node_access} with:

$record = array(
  'nid' => 0,
  'gid' => 888,
  'realm' => 'example_realm',
  'grant_view' => 1,
  'grant_update' => 0,
  'grant_delete' => 0,
);
drupal_write_record('node_access', $record);

And then in its hook_node_grants() implementation, it would need to return:

if ($op == 'view') {
  $grants['example_realm'] = array(888);
}

If you decide to do this, be aware that the node_access_rebuild() function will erase any node ID 0 entry when it is called, so you will need to make sure to restore your {node_access} record after node_access_rebuild() is called.

Parameters

$account: The user object whose grants are requested.

$op: The node operation to be performed, such as 'view', 'update', or 'delete'.

Return value

An array whose keys are "realms" of grants, and whose values are arrays of the grant IDs within this realm that this user is being granted.

For a detailed example, see node_access_example.module.

See also

node_access_view_all_nodes()

node_access_rebuild()

Related topics

File

modules/node/node.api.php, line 194

Hooks provided by the Node module.

Code

function hook_node_grants($account, $op) {
  if (user_access('access private content', $account)) {
    $grants['example'] = array(1);
  }
  $grants['example_owner'] = array($account->uid);
  return $grants;
}