Add another field?

While this isn’t possible via the UI, this is possible with a little custom code that you could drop in functions.php:

I’ll try to put together an example and post it here for you to try out.

That’d be great! Looking forward to seeing it

@jeremyomeara,

Sorry for the delay in getting this out. I just published version 1.3 of the plugin which was needed before I could send you a code sample.

This should do it:

// First we add the new birthday field to the checkout fields
function ss_wc_add_birthday_field( $checkout_fields ) {

	$opt_in_checkbox_display_location = 'billing';

	$field_id = 'birthday';
	$field_name = __( 'Birthday', 'ss_wc_mailchimp' );

	$checkout_fields[$opt_in_checkbox_display_location][$field_id] = array(
		'type'    => 'text',
		'label'   => esc_attr( $field_name ),
		'placeholder' => 'mm/dd'
	);

	return $checkout_fields;
}
add_filter( 'woocommerce_checkout_fields', 'ss_wc_add_birthday_field' );

// Make birthday a date picker mm/dd field
function ss_wc_add_checkout_field_datepicker() {
    if ( is_checkout() ) {
        $js = 'jQuery( "#birthday" ).css("width","125px").datepicker({ changeMonth: true, changeYear: true, yearRange:"-100:+0", dateFormat: "mm/dd" });';
        // Check if WC 2.1+
        if ( defined( 'WC_VERSION' ) && WC_VERSION ) {
            wc_enqueue_js( $js );
        } else {
            global $woocommerce;
            $woocommerce->add_inline_js( $js );
        }
    }
}
add_filter( 'wp_footer' , 'ss_wc_add_checkout_field_datepicker' );

// Save the birthday field with the order
function ss_wc_save_birthday_field( $order_id ) {
	$birthday = isset( $_POST['birthday'] ) ? $_POST['birthday'] : null;
	update_post_meta( $order_id, 'birthday', $birthday );
}
add_action( 'woocommerce_checkout_update_order_meta', 'ss_wc_save_birthday_field' );

// tie into the WooCommerce MailChimp 'ss_wc_mailchimp_subscribe_merge_vars' action filter to add the MailChimp merge var for Birthday
function ss_wc_send_birthday_field_to_mailchimp( $order_id, $merge_vars ) {
    // retrieve the birthday from the order meta/custom fields
    $birthday = get_post_meta( $order_id, 'birthday', true );

    // Add 'BIRTHDAY' merge variable to MailChimp call (change 'BIRTHDAY' to whatever your merge variable is called in MailChimp)
	$merge_vars['BIRTHDAY'] = $birthday;
    return $merge_vars;
}
add_filter( 'ss_wc_mailchimp_subscribe_merge_vars' , 'ss_wc_send_birthday_field_to_mailchimp', 10 , 2 );

[Moderator Note: Please post code & markup between backticks or use the code button. Your posted code may now have been permanently damaged by the forum’s parser.]

Hi there Anderly. Thanks for that mate, it’s showing the new birthday field fine and the subscription itself is working great, but it just wont pass the birthday information to MC properly. Any ideas?

Please use this updated code instead of that above. The above code had the filter function parameters in the wrong order.

// First we add the new birthday field to the checkout fields
function ss_wc_add_birthday_field( $checkout_fields ) {

	$opt_in_checkbox_display_location = 'billing';

	$field_id = 'birthday';
	$field_name = __( 'Birthday', 'ss_wc_mailchimp' );

	$checkout_fields[$opt_in_checkbox_display_location][$field_id] = array(
		'type'    => 'text',
		'label'   => esc_attr( $field_name ),
		'placeholder' => 'mm/dd'
	);

	return $checkout_fields;
}
add_filter( 'woocommerce_checkout_fields', 'ss_wc_add_birthday_field' );

// Make birthday a date picker mm/dd field
function ss_wc_add_checkout_field_datepicker() {
    if ( is_checkout() ) {
        $js = 'jQuery( "#birthday" ).css("width","125px").datepicker({ changeMonth: true, changeYear: true, yearRange:"-100:+0", dateFormat: "mm/dd" });';
        // Check if WC 2.1+
        if ( defined( 'WC_VERSION' ) && WC_VERSION ) {
            wc_enqueue_js( $js );
        } else {
            global $woocommerce;
            $woocommerce->add_inline_js( $js );
        }
    }
}
add_filter( 'wp_footer' , 'ss_wc_add_checkout_field_datepicker' );

// Save the birthday field with the order
function ss_wc_save_birthday_field( $order_id ) {
	$birthday = isset( $_POST['birthday'] ) ? $_POST['birthday'] : null;
	update_post_meta( $order_id, 'birthday', $birthday );
}
add_action( 'woocommerce_checkout_update_order_meta', 'ss_wc_save_birthday_field' );

// tie into the WooCommerce MailChimp 'ss_wc_mailchimp_subscribe_merge_vars' action filter to add the MailChimp merge var for Birthday
function ss_wc_send_birthday_field_to_mailchimp( $merge_vars, $order_id ) {
    // retrieve the birthday from the order meta/custom fields
    $birthday = get_post_meta( $order_id, 'birthday', true );

    // Add 'BIRTHDAY' merge variable to MailChimp call (change 'BIRTHDAY' to whatever your merge variable is called in MailChimp)
	$merge_vars['BIRTHDAY'] = $birthday;
    return $merge_vars;
}
add_filter( 'ss_wc_mailchimp_subscribe_merge_vars' , 'ss_wc_send_birthday_field_to_mailchimp', 10 , 2 );

Thanks for updating the code anderly but the birthday value is still not getting passed for me. I can see the following in the debug.log:

[vars] => Array
        (
            [FNAME] => Caroline Elisa
            [LNAME] => Haggerty

            [BDAY] => 18/08/1980
        )

In Mailchimp, BDAY is the merge tag, I’ve also tried with MERGE4:
https://monosnap.com/image/Ann6AwvufzUlDZRL4YtNycnzt6pIT5

Are you getting an error in the log? Also, what data type do you have BDAY set to in MailChimp?

There is no error message and the subscriber is being created on order creation. The full output is:

[18-Feb-2015 01:53:10 UTC] Order Opt-In Value: ''
[18-Feb-2015 01:53:10 UTC] Subscribe customer ([email protected]) to list cd042f4bc3
[18-Feb-2015 01:53:10 UTC] Calling MailChimp API listSubscribe method with the following: Array
(
    [listid] => cd042f4bc3
    [email] => [email protected]
    [vars] => Array
        (
            [FNAME] => Caroline Elisa
            [LNAME] => Haggerty
            [GROUPINGS] => Array
                (
                    [0] => Array
                        (
                            [name] => Groups
                            [groups] => Customer
                        )

                )

            [BDAY] => 18/08/1980
        )

    [email_type] => html
    [double_optin] => 1
    [update_existing] => 1
    [replace_interests] =>
    [send_welcome] =>
)

[18-Feb-2015 01:53:11 UTC] MailChimp API response: %s

The field is a date field in Mailchimp (to include the year). Here are the settings: https://monosnap.com/image/Ann6AwvufzUlDZRL4YtNycnzt6pIT5

And here is the sign up form URL: https://eepurl.com/8Lqin