I have a field which I don't want to be displayed for certain users, however I still want a value to be entered for that field, which is extrapolated from other fields they enter data in.
In order to do this, I'm setting the field as hidden in
$form['field_target']['#type'] = 'hidden';
and then setting the value of the field from within a form_validate function based on another field, such as:
$form_state['values']['field_target']['und']['0'] = $form_state['values']['field_source']['und']['0'];
And this works fine, unless I force a form validation error on field_source. When I correct the validation error and submit again, I get a white screen with PHP Error:
PHP Fatal error: Cannot create references to/from string offsets nor overloaded objects in includes/common.inc on line 6288
This error happens even if I comment out the setting of field_target. However I can fix this error by removing the
[#type'] = 'hidden' line and everything works fine, except that the field shows for all users.
Is there any way to fix my above approach, or is there a better way to achieve what I'm trying to do?