WooCommerce Custom Fields - Multiselect

Question

I'm adding extra fields to the checkout page in WooCommerce, I can add basic fields like a text box, but need to add a (multi) select box, where the user can choose multiple items. I've figured out how to add a select box through code, like this:

add_action('woocommerce_after_order_notes', 'my_custom_checkout_field');

function my_custom_checkout_field( $checkout ) {

    echo '<div id="my_custom_checkout_field"><h3>'.__('My Field').'</h3>';

    woocommerce_form_field( 'my_field_name', array(
        'type'          => 'select',
        'class'         => array('my-field-class form-row-wide'),
        'label'         => __('Fill in this field'),
        'placeholder'       => __('Enter something'),
        'options'           => array(
            'Buick' => __('Buick', 'woocommerce' ),
            'Ford' => __('Ford', 'woocommerce' )
        )
        ), $checkout->get_value( 'my_field_name' ));

    echo '</div>';

}

But that's just a single select drop down.
Can I do something similar for a multi-select?
Or do you have a WooCommerce extension that'd you recommend?

Please advice, thanks in advance!

Answer 1

Although it's late to answer this post but I am adding this solution for the help of those still looking for the solution. We can add custom data using custom_attributes that will make it a multiple-choice dropdown.

woocommerce_form_field('my_field_name',array(
   type=>"select",
   custom_attributes=>array("multiple"),
   options=>$options
));

Answer 2

You need to create your own custom field type handler. If you look at WooCommerce source code you will see that you can use filter: 'woocommerce_form_field_' . $args['type']

I haven't really tested this, this is just slightly altered code from single "select" control, but you get the point:

add_filter( 'woocommerce_form_field_multiselect', 'custom_multiselect_handler', 10, 4 );

function custom_multiselect_handler( $field, $key, $args, $value ) {

    $options = '';

    if ( ! empty( $args['options'] ) ) {
        foreach ( $args['options'] as $option_key => $option_text ) {
            $options .= '<option value="' . $option_key . '" '. selected( $value, $option_key, false ) . '>' . $option_text .'</option>';
        }

        if ($args['required']) {
            $args['class'][] = 'validate-required';
            $required = '&nbsp;<abbr class="required" title="' . esc_attr__('required', 'woocommerce') . '">*</abbr>';
        }
        else {
            $required = '&nbsp;<span class="optional">(' . esc_html__('optional', 'woocommerce') . ')</span>';
        }

        $field = '<p class="form-row ' . implode( ' ', $args['class'] ) .'" id="' . $key . '_field">
            <label for="' . $key . '" class="' . implode( ' ', $args['label_class'] ) .'">' . $args['label']. $required . '</label>
            <select name="' . $key . '" id="' . $key . '" class="select" multiple="multiple">
                ' . $options . '
            </select>
        </p>' . $args['after'];
    }

    return $field;
}

And in your code just state the type as 'multiselect':

add_action('woocommerce_after_order_notes', 'my_custom_checkout_field');

function my_custom_checkout_field( $checkout ) {

    echo '<div id="my_custom_checkout_field"><h3>'.__('My Field').'</h3>';

    woocommerce_form_field( 'my_field_name', array(
        'type'          => 'multiselect',
        'class'         => array('my-field-class form-row-wide'),
        'label'         => __('Fill in this field'),
        'placeholder'   => __('Enter something'),
        'options'       => array(
            'Buick' => __('Buick', 'woocommerce' ),
            'Ford' => __('Ford', 'woocommerce' )
        )
        ), $checkout->get_value( 'my_field_name' ));

    echo '</div>';

}