developed.be

• Published:November 22nd, 2012
• Category:Drupal, Drupal 6, Drupal Forms

The short answer:

It’s not possible

The long answer:

In a simple user form it is possible to add a single on/off checkbox.

  $form['thermometer_enabled'] = array(
    '#type' => 'checkbox',
    '#title' => t('Show the thermometer'),
    '#options' => array(0 => t("no"), 1 => t("yes")),
  );

But, it’s not possible to provide a default value (checked/unchecked) with a single chechbox. This causes difficulties when you want to show the saved value of a user.

A simple solution is to use a “yes/no radiobutton list” instead of a single checkbox.

  $form['thermometer_enabled'] = array(
    '#type' => 'radios',
    '#title' => t('Show the thermometer'),
    '#options' => array(0 => t("no"), 1 => t("yes")),
    '#default_value' => variable_get('thermometer_enabled', 0),
  );

In this example the result is saved in the variable thermomoeter_enabled and has the default value of 0 (false).