How to set Form API date_select option values

Question

Creating a date_select field in a custom form, like this:

$date_format = "Y-m-d";
$form['birth_date'] = array(
    '#type' => 'date_select',
    '#title' => t('Date of birth'),
    '#default_value' => NULL,
    '#date_type' => DATE_FORMAT_UNIX,
    '#date_timezone' => date_default_timezone(),
    '#date_format' => $date_format,
    '#date_increment' => 1,
    '#date_year_range' => 'now:1910',
    '#date_label_position' => 'within',
    '#required' => TRUE,
);

The element it generates for the year dropdown is like this

<select>
  <option value="0">-Year</option>
  <option value="1">2017</option>
  <option value="2">2016</option>
  <option value="3">2015</option>
   .
   .
   .
  <option value="108">1910</option>
</select>

The year value returned in $form_state['values'] is the value of the option, e.g. if 2017 is chosen the value returned is 1. Is it possible to somehow set the option values like this instead

<option value="2016">2016</option> 

so that the actual year will be returned?

Answer 1

This is how I get when I copied your code without any change. Option values are correct, but somehow the order got reversed.

<select class="date-year form-select" id="edit-birth-date-year" name="birth_date[year]">
    <option value="" selected="selected">-Year</option>
    <option value="1910">1910</option>
    <option value="1911">1911</option>
    <option value="1912">1912</option>
    .
    .
    .
    <option value="2017">2017</option>
</select>

Check your Date / Date API module versions. I'm using 7.x-2.8