I'm trying to add a field to my query by using addField(). However, whenever I add this to the query I get a whitescreen and an apache error message on the line after. Any help in resolving this would be much appreciated.

Apache error log:

PHP Fatal error: Call to a member function extend() on a non-object

db_select query:

$query = db_select('z_revision', 't')
    ->fields('t', array('drupal_user_id'))
    ->addField('t', 'z', 'category')
    ->extend('PagerDefault') # error on this line

Ideally this would give me a two column table with headers 'drupal_user_id' and 'category' - all the rows in the category column having 'z' as a value.

1 Answer 1


addField returns the alias of the field that's added, not the query object. You just need to break your code up a bit:

$query = db_select('z_revision', 't')
  ->fields('t', array('drupal_user_id'));

$query->addField('t', 'z', 'category');

$result = $query->extend('PagerDefault')
  • Thanks Clive. That cleared the error but now I get a new one. Is addField() the best way to create a totally new arbirary field in my query results? I'm getting a Column not found in field list error now. Hoping to do something similar to this: stackoverflow.com/questions/3769702/…
    – RobotEyes
    Commented Jul 8, 2015 at 15:50
  • The easiest way to debug is to cast the query object to a string before you execute it - that's give you the raw SQL, should make it a lot easier to spot what's going wrong. It's difficult to guess what you're looking for without knowing the structure of the tables
    – Clive
    Commented Jul 8, 2015 at 15:58
  • 2
    Thanks Clive - I managed add a column on the fly using addExpression() api.drupal.org/comment/33553#comment-33553
    – RobotEyes
    Commented Jul 8, 2015 at 16:03

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