WooCommerce conditional custom checkout fields

Question

In WooCommerce, I\'m currently trying to add a conditional custom field in the Checkout that shows a checkbox which if is checked displays an input field to insert an italia

Answer 1

In this answer I can't treat PDF invoice, so you will get here:

• Solving the problem of conditional "required" field (point 1)
• Solving the problem of the json error (point 2)
• Displayed only for italian language (point 3)

Additionally I have:

• Revisited all your code and corrected many little errors.
• Added code to display and edit the backend user profile custom field value "codice fiscale":
  
  

Here is the code:

add_filter( 'woocommerce_checkout_fields' , 'cbi_cf_chkbox' );
function cbi_cf_chkbox ( $fields ) {
    if ( ICL_LANGUAGE_CODE !='it' ) return $fields; // Only for Italy

    $fields['billing']['checkbox_cf'] = array(
        'type'      => 'checkbox',
        'label'     => __('Voui la fattura? (solo per privati)', 'cbi-custom-parts'),
        'class'     => array('form-row-wide'),
        'clear'     => true
     );

    $fields['billing']['cf_in'] = array(
        'label'     => __('Inserisci il codice fiscale', 'cbi-custom-parts'),
        'placeholder'   => _x('RSSMRA85T10A562S', 'placeholder', 'cbi-custom-parts'),
        'class'     => array('form-row-wide'),
        'clear'     => true
     );

    return $fields;
}

add_action( 'woocommerce_after_checkout_form', 'cbi_cf_conditionally_hide_show', 6);
function cbi_cf_conditionally_hide_show() {
    if ( ICL_LANGUAGE_CODE !='it' ) return; // Only for Italy
    $required = esc_attr__( 'required', 'woocommerce' );
    ?>
    <script type="text/javascript">
        (function($){
            var required = '<abbr class="required" title="<?php echo $required; ?>">*</abbr>'; // Required html

            $('#cf_in_field > #cf_in').prop('pattern', "^[a-zA-Z]{6}[0-9]{2}[a-zA-Z][0-9]{2}[a-zA-Z][0-9]{3}[a-zA-Z]$"); // Doesn't seem to do something
            $('#cf_in_field').hide();

            $('input#checkbox_cf').change(function(){
                if (this.checked) {
                    $('#cf_in_field').fadeIn("fast", function(){
                        $(this).addClass("validate-required");
                        $('#cf_in_field > label').append(required);
                    });
                } else {
                    $('#cf_in_field').fadeOut("fast", function(){
                        $(this).removeClass("validate-required");
                        $('#cf_in_field > label > .required').remove();
                    });
                }
                $('#cf_in_field').val('');
                $('#cf_in_field').removeClass("woocommerce-validated");
                $('#cf_in_field').removeClass("woocommerce-invalid woocommerce-invalid-required-field");
            });
        })(jQuery);
    </script>
    <?php
}

// Utility function checking "codice fiscale" validity
function is_cf_valid( $valore, $codice_fiscale = true ){
    $espressione = "^[a-z]{6}[0-9]{2}[a-z][0-9]{2}[a-z][0-9]{3}[a-z]$";
    if( ! $codice_fiscale ) $espressione = "^[0-9]{11}$";
    return eregi( $espressione, $valore ) ? true : false;
}

// Check custom fields value "codice fiscale" when submit and return error notices (if needed)
add_action('woocommerce_checkout_process', 'cbi_cf_process');
function cbi_cf_process() {
    if ( isset($_POST['checkbox_cf']) && $_POST['checkbox_cf'] == 1 ) {
        if( empty( $_POST['cf_in'] ) ) {
            wc_add_notice( __( "Please don't forget to enter your Codice Fiscale/Partita Iva", "cbi-custom-parts" ), "error" );
        } else {
            $valid_codice_fiscale = is_cf_valid( $_POST['cf_in'] );
            if( ( ! $valid_codice_fiscale ) )
                wc_add_notice( __( "Wrong data in Codice Fiscale/Partita Iva field", "cbi-custom-parts" ), "error" );
        }
    }
}

// Save the custom field value "codice fiscale" in order meta and in user meta
add_action( 'woocommerce_checkout_update_order_meta', 'cbi_cf_in_update_order_meta' );
function cbi_cf_in_update_order_meta ( $order_id ) {
    if ( empty( $_POST['cf_in'] ) ) return;

    $customer_id = get_post_meta( $order_id, '_customer_user', true );
    $user_codice_fiscale = get_user_meta( $order_id, 'codice_fiscale', true );

    if( ! empty( $user_codice_fiscale ) )
        update_user_meta($order->user_id, 'codice_fiscale', sanitize_text_field( $_POST['cf_in'] ) );

    update_post_meta( $order_id, '_codice_fiscale', sanitize_text_field( $_POST['cf_in'] ) );
}

// Backend : Display in Order edit pages, after billing address, the custom field value "codice fiscale"
add_action( 'woocommerce_admin_order_data_after_billing_address', 'cbi_cf_admin_order_data_after_billing_address', 10, 1 );
function cbi_cf_admin_order_data_after_billing_address( $order ){
    $codice_fiscale = get_post_meta( $order->get_id(), '_codice_fiscale', true );
    if( ! empty( $codice_fiscale ) )
        echo '<p><strong>'.__('Codice Fiscale', 'cbi-cf-invoice').':</strong> ' . $codice_fiscale . '</p>';
}

// Backend: Display and edit user profile custom field value "codice fiscale" Only for Italy
add_action( 'show_user_profile', 'add_extra_user_codice_fiscale', 1, 1 );
add_action( 'edit_user_profile', 'add_extra_user_codice_fiscale', 1, 1 );
function add_extra_user_codice_fiscale( $user )
{

    //if( get_user_meta( $user->ID, 'billing_country', true ) != 'IT' ) return;  // Only for Italy
    $codice_fiscale = get_user_meta( $user->ID, 'codice_fiscale', true );
    if( empty( $codice_fiscale ) ) $codice_fiscale = '';
    ?>
        <h3><?php _e( "Codice fiscale", "cbi-custom-parts" ); ?></h3>
        <table class="form-table"><tr>
            <th><label for="codice_fiscale"><?php _e( "Codice fiscale", "cbi-custom-parts" ); ?></label></th>
            <td><input type="text" name="codice_fiscale" value="<?php echo esc_attr($codice_fiscale); ?>" class="regular-text" /></td>
        </tr></table><br />
    <?php
}

// Backend: Save edited user profile custom field value "codice fiscale" Only for Italy
add_action( 'personal_options_update', 'save_extra_user_codice_fiscale' );
add_action( 'edit_user_profile_update', 'save_extra_user_codice_fiscale' );
function save_extra_user_codice_fiscale( $user_id )
{
    if( ! empty( $_POST['codice_fiscale'] ) )
        update_user_meta( $user_id, 'codice_fiscale', sanitize_text_field( $_POST['codice_fiscale'] ) );
}

Code goes in function.php file of your active child theme (or theme) or also in any plugin file.

All code is tested on Woocommerce 3+ and works.