Drupal 7 Module Development

Chapter 7
}
}
'#type' => 'select',
'#title' => t('How many dimensions'),
'#options' => array(
2 => t('Height and width'),
3 => t('Height, width, and depth'),
),
'#default_value' => $settings['num_dimensions'],
'#required' => FALSE,
'#description' => t(
'Is this for a 2-dimensional or 3-dimensional object?'),
);
return $form;
We only have a single form element here, that is, a select box that lets the user select
whether we're dealing with a 2-dimensional or 3-dimensional object. It is this value
that will determine the structure of the field itself, as defined in the schema callback.
Field validation
Although there are a couple of other callbacks we could implement, there's only one
that we will cover for now, as it is rather important, namely, validation.
function dimfield_field_validate($obj_type, $object, $field,
$instance, $langcode, &$items,
&$errors) {
if ($field['type'] == 'dimensions')'' {
$columns = array(
'height' => 'max_height',
'width' => 'max_width',
);
if ($field['settings']['num_dimensions'] == 3) {
$columns['depth'] = 'max_depth';
}
foreach ($items as $delta => $item) {
foreach ($columns as $column => $max_key) {
if ($instance['settings'][$max_key] &&
!empty($item[$column]) &&
$item[$column] > $instance['settings'][$max_key]) {
$errors[$field['field_name']][$delta][] = array(
'error' => 'dimfield_' . $max_key,
'message' => t(
'%name: The %column may not be larger than %max.',
array('%column' => $column,
'%name' => $instance['label'],
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