Can someone tell me what I am doing wrong? This is my first time using \_\_toString. I receiving the follwoing error: `Catchable fatal error: Method users_class::__toString() must return a string value`

This is my call to the object using Smarty:

```
 {assign var='udatas' value="$userObj->fetchUser(array('id'=>$ststres[ststval].to_id))"}

```

This is the object.

```
class users_class {

protected $users_class;

public function __toString() {

    return $this->users_class;
}
  public function fetchUser(array $conditions){
            $db = Core::getInstance();

            $sql = "SELECT * FROM ".USERS." WHERE ";
            $i=0;
            $params = array();
            //$where = array();
            foreach ($conditions as $column => $value) {
            if (preg_match('/^[a-z-.-_]+$/', $column)) {
                if($i!=0){
                    $sql .= " AND ";
                }
            $sql .= "$column = ?";
            $params[] = $value;
            $i++;

    }
   }            
            //$sql .= implode(' AND ', $where);
            //$sql .= " order by title asc";    
            $res = $db->dbh->prepare($sql);
            $res->execute(array_values($params));
            return $res->fetch(PDO::FETCH_ASSOC);               
}   
   }

```