The Greek VAT ID validator checks if a number is POTENTIALLY valid in Greek VAT ID Registry.

Validator does NOT check if VAT ID does actually belong to a person or a company, it checks only if it obeys the algorithm of a valid Greek VAT ID:

1. VAT ID = 090000045
2. Calculate sum of 0*2^8+9*2^7+0*2^6+0*2^5+0*2^4+0*2^3+0*2^2+4*2^1 = 1160
3. Calculate mod11 = 1160 % 11 = 5
4. Calculate mod10 = 5 % 10 = 5
5. mod10 (5) is equal to 5 (last digit), so VAT ID is VALID

1. VAT ID = 123456789
2. Calculate sum of 1*2^8+2*2^7+3*2^6+4*2^5+5*2^4+6*2^3+7*2^2+8*2^1 = 1004
3. Calculate mod11 = 1004 % 11 = 3
4. Calculate mod10 = 3 % 10 = 3
5. mod10 (3) is not equal to 9 (last digit), so VAT ID is INVALID

Install the package using Composer:

composer require liagkos/laravel-grvatid-validator

Laravel's service provider discovery will automatically configure the Grvatval service provider for you.

After installation, the grvatval validator will be available for use directly in your validation rules.

'vatid' => 'grvatval',

Within the context of a registration form, it would look like this:

return Validator::make($data, [
    'name' => 'required',
    'email' => 'required|string|email',
    'password' => 'required',
    'vatid' => 'required|grvatval'
]);

Alternatively, you can use the Liagkos\Grvatval\Grvatval Validation Rule Object instead of the grvatval alias if you prefer:

return Validator::make($data, [
    'name' => 'required',
    'email' => 'required|string|email',
    'password' => 'required',
    'vatid' => ['required', new \Liagkos\Grvatval\Grvatval],
]);

You will need to assign your own validation message within the resources/lang/*/validation.php file(s). Both the Rule object and the grvatval validator alias refer to the validation string validation.grvatval.

Just run the the test in tests directory. I use the orchestra/testbench along with PHPUnit.

Since I'm quite new in all Laravel stuff, I got the idea from Stephen Rees-Carten and his own valorin/pwned-validator validator, from whom I used some code and README.md stuff, modified accordingly to make this validator. Thank you Stephen, live long and propsper!