The element's name property is declared in the $form array, at the very end of the array tree. For example, if an element in the form tree was structured like this: $form['account_settings']['username'] ?>

...then that element's name property is 'username'--this is the key it will be available under in $form_state['values'], in your validation and submission functions, as the form code flattens the array in this fashion before it passes the key/value pairs. NOTE: if you wish to have the full tree structure passed to $form_state['values'], this is possible, and will be discussed later.


So, for example, if you have this:

$form['details']['admin'] = array(
    '#type' => 'checkbox',
    '#title' => t('Only admin can view'),
    '#default_value' => variable_get('admin', 0),

You see that you'd be using variable_get('admin', 0);

So what's to prevent naming collisions? Say you have another setting:

$form['more_details']['admin'] = array(
        '#type' => 'checkbox',
        '#title' => t('Only admin can view'),
        '#default_value' => variable_get('admin', 0),

If anyone has a clear explanation as to how this "flattening" works, that'd be great.

1 Answer 1


While it's good practice to use unique field names in your form, you can use the #tree property to preserve the group nesting of parent -> same child name there.

$form['#tree'] = TRUE;

That will preserve the nesting of group -> field values in the form $form_state['values'] so instead of being flattened it will be

$form_state['values']['details']['admin'] = 'foo';


$form_state['values']['more_details']['admin'] = 'bar';
  • True, but when it comes to using variable_get after you save the form, what will the difference in variable names be?
    – AlxVallejo
    Oct 15, 2013 at 13:49
  • @AlxVallejo, the variable will be an array with nested values. Aug 22, 2016 at 22:28

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