Display the flag link only for the node author

Question

I'm trying to display the flag link only for the node author, and I'm using the following code:

global $user;
if ($node->uid == $user->uid) {
  //print your flag
}

The link doesn't appear.

Do you have any idea on what is causing this?

Answer 1

You may use hook_flag_access(), as in the following code.

 function crystal_qa_flag_access($flag, $entity_id, $action, $account) {
   // Only the author of the question has right to use flag "Accepeted" on answers.
   if (($flag->name == 'accepted') && ($flag->content_type == 'node')  && ($node = node_load($entity_id))) {
     if ($node->type=='answer') {
       // The content type machine name must be answer.
       $question_nid = $node->field_answer['und']['0']['target_id'];
       $question = node_load($question_nid);
       return ($question->uid == $account->uid);
     }
   }
 }

Answer 2

Perhaps by declaring $user to be a blank variable right before you use it, you're overwriting Drupal's variable?