Collect birthdate on checkout

pmpro-birthday-validation.php

<?php
/*
Add birthday to user signup and check that user is between 13-17.

Will not work with PayPal Standard or PayPal Express.
*/
//birthday fields
function my_pmpro_checkout_after_user_fields()
{
    $current_day = date("j");
    $current_month = date("M");
    $current_year = date("Y");

    global $current_user;

    if ( empty($current_user->user_email) )
    {
        //Check whether birthday field is set for the user checking in
        $email = isset($_REQUEST['bemail']) ? $_REQUEST['bemail'] : null;

        if (!empty($email))
            $user = get_user_by('email', sanitize_email($email));
        else
            $user = pmpro_set_current_user();
    }
    else {
        $user = $current_user;
    }

    $bday_date = get_user_meta($user->ID, 'birthday', true);

    if (false === $bday_date) {

        // birthday info set in form
        if (isset($_REQUEST['birthday_month']))
        {
            $bday = intval( $_REQUEST['birthday_day'] );
            $bmonth = intval( $_REQUEST['birthday_month'] );
            $byear = intval( $_REQUEST['birthday_year'] );

            $bday_date = "{$byear}-{$bmonth}-{$bday}";
        }
    }

    if (empty($bday_date))
        $bday_date = "{$current_year}-{$current_month}-{$current_day}";

    //Birthday: '1981-01-10' => array( 1981, 01, 10 );
    $bday_arr = explode('-', $bday_date);

    ?>
<div>
    <label for="birthday_month">Birthday</label>
    <select name="birthday_month">
        <?php
        for($i = 1; $i < 13; $i++)
        {
            ?>
            <option value="<?php echo $i?>" <?php selected($i, $bday_arr[1], true); ?>><?php echo date("M", strtotime($i . "/1/" . $bday_arr[0]))?></option>
            <?php
        }
        ?>
    </select>
    <input type="text" name="birthday_day" size="4" placeholder="day" value="<?php echo $bday_arr[2]; ?>" />
    <input type="text" name="birthday_year" size="8" placeholder="year" value="<?php echo $bday_arr[0]; ?>" />
    <small>month/dd/yyyy</small>
</div>
<?php
}
add_action("pmpro_checkout_after_user_fields", "my_pmpro_checkout_after_user_fields");

//checking birthday
function my_pmpro_registration_checks($okay)
{
    if(!$okay)
        return $okay;		//there are other errors to handle

    global $pmpro_msg, $pmpro_msgt;

    $birthday_month = isset($_REQUEST['birthday_month']) ? intval($_REQUEST['birthday_month']) : null;
    $birthday_day = isset($_REQUEST['birthday_day']) ? intval($_REQUEST['birthday_day']) : null;
    $birthday_year = isset($_REQUEST['birthday_year']) ? intval($_REQUEST['birthday_year']) : null;

    //make sure they entered any birthday
    if(empty($birthday_month) || empty($birthday_day) || empty($birthday_year))
    {
        $pmpro_msg = "Please enter a birthday.";
        $pmpro_msgt = "pmpro_error";
        return false;
    }

    //make sure birthday is between 13-17
    $age = my_getAge($birthday_year . "-" . $birthday_month . "-" . $birthday_day);
    if($age < 13 || $age > 17)
    {
        $pmpro_msg = "You must be between 13 and 17 years old.";
        $pmpro_msgt = "pmpro_error";
        return false;
    }

    return $okay;
}
// add_filter("pmpro_registration_checks", "my_pmpro_registration_checks");

//age function #3 from: http://spyk3lc.blogspot.com/2012/03/php-get-age-comparison-results-of-3.html
function my_getAge($date) // Y-m-d format
{
    return intval(substr(date('Ymd') - date('Ymd', strtotime($date)), 0, -4));
}

//saving birthday
function my_pmpro_after_checkout($user_id)
{
    if(!empty($_REQUEST['birthday_month']))
    {
        $birthday_month = intval($_REQUEST['birthday_month']);
        $birthday_day = intval($_REQUEST['birthday_day']);
        $birthday_year = intval($_REQUEST['birthday_year']);

        //save birthday
        $birthday = $birthday_year . "-" . $birthday_month . "-" . $birthday_day;
        update_user_meta($user_id, "birthday", $birthday);
    }
}
add_action("pmpro_after_checkout", "my_pmpro_after_checkout");
add_action("pmpro_checkout_before_processing", "my_pmpro_after_checkout");

function my_extra_csv_cols($extra_cols)
{
    $extra_cols[] = array('metavalues', 'pmpro_birthday');
    return $extra_cols;
}
add_filter('pmpro_members_list_csv_extra_columns', 'my_extra_csv_cols');