title: Catchable fatal error: Object could not be converted to string
body: <p>In my Zend Framework application I'm getting this error: </p>
  
  <p><code>Catchable fatal error: Object of class User could not be converted to string in /home/trengine/domains/completeset.us/application/models/User.php on line 121</code></p>
  
  <p>Line 121 is the where clause in this mySql query: </p>
  
  <pre><code>$query = "SELECT first,
                           last,
                           email,
                           gender,
                           user_type,
                           country,
                           state,
                           province,
                           city,
                           DATE_FORMAT(birthday, '%m/%d/%Y') AS birthday,
                           facebook_id
                           FROM users
                           WHERE user_id = '{$this-&gt;id}'";
  </code></pre>