Skip Woocommerce checkout field validation if field data is not present

[Sathyaprakash]

I have added a custom code to validate the phone numbers to be 10 digits on checkout fields.

Here is the code

add_action('woocommerce_checkout_process', 'phone_number_validation');

function phone_number_validation() {

global $woocommerce;

if ( ! (preg_match('/^[0-9]{10}$/D', $_POST['billing_phone'] ))){

wc_add_notice( "Incorrect Phone Number! Please enter valid 10 digits phone number"  ,'error' 
);

}
}

As i need alternate numbers in billing field we added one more phone number field(which is optional).

I used the same code for alternate field validation with 10 digits but i cant able to submit form since it ask me to enter phone number in that alternate field also.

Since its a optional fields i need to skip validation if no phone number entered. on other hand if phone number is entered on that field it should be validated for minimum 10 digit.

[rproffitt]

I take it this doesn't have to work world wide? See https://en.wikipedia.org/wiki/Telephone_numbering_plan

[Dani]

This is completely irrelevant, but perhaps it will help in the future. PHP has a built-in filter_var() function that automatically validates that an appropriately formatted email, URL, etc. have been typed in. The only reason I bring this up is because for some reason I thought that phone numbers might be included in that function, so I checked, but alas they're not.

You can change line 7 to be:

if (!empty($_POST['billing_phone']) && ! (preg_match('/^[0-9]{10}$/D', $_POST['billing_phone'] ))){

This should only show the error message if it's both not empty and doesn't match the criteria.