What's the best way to validate numbers with comma as decimal separator?

Question

In a Laravel app, I have a form on which I need to validate numbers with a comma as the decimal separator. For the moment, it only works with a point because my validation r

Answer 1

Building on the excellent answer from The Alpha, here is a code snippet to make a float validation configurable.

Add this snippet to the boot() function in your AppServiceProvider class (tested with Laravel 5.4):

Validator::extend('float', function ($attribute, $value, $parameters, $validator) {
    $thousandsSeparator = env('APP_NUMBER_THOUSANDS_SEPARATOR') == '.' ? '\\' . env('APP_NUMBER_THOUSANDS_SEPARATOR') : env('APP_NUMBER_THOUSANDS_SEPARATOR');
    $commaSeparator = env('APP_NUMBER_COMMA_SEPARATOR') == '.' ? '\\' . env('APP_NUMBER_COMMA_SEPARATOR') : env('APP_NUMBER_COMMA_SEPARATOR');
    $regex = '~^[0-9]{1,3}(' . $thousandsSeparator . '[0-9]{3})*' . $commaSeparator . '[0-9]+$~';
    $validate = preg_match($regex, $value);

    if ($validate === 1) {
        return true;
    }

    return false;
});

Your .env-file would have those two lines:

APP_NUMBER_COMMA_SEPARATOR="."
APP_NUMBER_THOUSANDS_SEPARATOR=","

And your rule would look like this:

$rules = [
    'amount' => 'float|min:0',
];

Note: I'm only escaping the . correctly. If you are going to use charaters that have special meaning in regex syntax (like * or +) you have to escape them too.

But since a float number like 550*345,00 (550,345.00) or 57+44 (57.44) wouldn't make sense I've ignored this issue.

Kind regards