Useful snippets

If you want to add extra functionality to your store, besides plugins you can also use pieces of code called snippets. You can add them to a child theme (a derived theme), if you use one, or with a plugin such as Code Snippets, which lets you insert them even if you’re not a programmer.

Below are a few useful ones that may come in handy if you use the Kybernaut Mailstep plugin.

Phone validation

If you don’t use any phone-validation plugin, I recommend at least a basic restriction in the form of this snippet. When the data is submitted at Checkout, it verifies the minimum length and watches for invalid characters in the phone field.

/**
 * @snippet      WooCommerce: Minimum phone number length
 * @author       Karolína Vyskočilová (https://kybernaut.cz)
 * @testedwith   WordPress 5.2 & WooCommmerce 3.7.0
 */

function my_theme_validate_phone( $fields, $errors ){
  // Mild phone check, min 9 numbers
  if ( ! preg_match('/^[+]?[0-9. -]{9,}$/', $fields['billing_phone']) && !empty( $fields['billing_phone'] ) ) {
    $errors->add( 'validation', __( '<strong>Phone number</strong> is not valid.', 'my-theme'  ) );
  }
}
add_action( 'woocommerce_after_checkout_validation', 'my_theme_validate_phone', 10, 2);

Tip

This snippet is just a basic safety net — it checks length and allowed characters, but it won’t add the country code, validate the number against the destination country’s format, or standardize numbers for your CRM, SMS gateway, or carrier. For a complete solution, check out my Phone Validator & Formatter plugin — it automatically adds the country code, validates against the country’s format, and standardizes formatting across your store.

House number validation

The snippet checks whether at least one digit is present in the first address line, on the assumption that the sender didn’t forget to include the house number. Useful for GLS and other delivery services.

/**
 * @snippet      WooCommerce: Street (first line) contains at least one digit (house number)
 * @author       Karolína Vyskočilová (https://kybernaut.cz)
 * @testedwith   WordPress 5.8 & WooCommmerce 5.5
 */

function my_theme_validate_street( $fields, $errors ){
  if ( ! preg_match('/[0-9]+/', $fields['billing_address_1']) && !empty( $fields['billing_address_1'] ) ) {
    $errors->add( 'validation', __( '<strong>Street address</strong> must contain a house number.', 'my-theme'  ) );
  }
}
add_action( 'woocommerce_after_checkout_validation', 'my_theme_validate_street', 10, 2);