Question

I want to disallow a node from publishing if there is another node already published with the same title. But I don’t know how to prevent a node from publishing. Any suggestions?

function example_nodeapi(&$node, $op, $teaser, $page) {                         
  switch ($op) {                                                              
    case 'validate':   
      // Indicate that it doesn't validate?                                                             
    break;
  } 
}    

Answer 1

It should be something like this

function example_nodeapi(&$node, $op, $teaser, $page) {
  switch ($op) {
    case 'validate':
      // Indicate that it doesn't validate?
      $sql = "SELECT nid FROM {node} WHERE title LIKE '%s'";
      $result = db_result(db_query($sql, trim($node->title)));
      if ($result) {
        // Node with such title exist! Set error or warning!
        form_set_error('title', 'Alert! Node with such title exist!').
      }
    break;
  }
}