Drupal 7 Module Development

Chapter 9
We may alter any element of this array, adding or removing items that suit our
business rules. Remember, however, that the resulting array will be used to write a
JOIN query to the {node_access} table. It may help to read the above array in that
context. A standard node query might run a simple SELECT:
SELECT title, nid FROM node WHERE status > 0 ORDER BY sticky, created
LIMIT 10;
When the node access grants are applied, the query will be executed as:
SELECT n.title, n.nid FROM node n INNER JOIN node_access na ON n.nid =
na.nid WHERE (na.realm = 'role_access' AND na.gid = 2) AND n.status >
0 ORDER BY sticky, created LIMIT 10;
As a module author, it is your responsibility to understand how these queries will be
rewritten so that your code can produce the desired results.
Remember that the grant ids are the array values, not the array
keys for your node access realm!
Now that we know how the query will be affected, we can write the code to add the
grant necessary to make anonymous users act like authenticated users.
/**
* Implement hook_node_grants_alter().
*/
function role_access_extend_node_grants_alter(&$grants, $account, $op)
{
// We only act on the 'view' operation.
// If our grant is not present, do nothing.
if ($op != 'view' || !isset($grants['role_access'])) {
return;
}
}
// Get the defined role id for 'authenticated user'.
$rid = DRUPAL_AUTHENTICATED_RID;
// Check the permission and set the grant.
if (user_access('view role access as authenticated user')) {
$grants['role_access'][] = $rid;
}
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