Laravel regex validation for empty string

Question

I have the following validation,
it should match string with letters,numbers,dashes. And empty input should also be valid.
The normal string validation is ok, but I can not make it match "empty" input.

'letter_code' => 'regex:/^[A-Za-z0-9\-]*$/'

letter_code format is invalid

tests :
"C14" // valid
"3.14" // "format is invalid", as expected
"-" // valid
"" // "format is invalid", NOT expected

Answer 1

I just found out in laracasts forum , that there is a nullable rule.
You can read about it in the official docs .

Without the nullable rule empty strings are considered invalid if there is a regex rule as well.

Answer 2

If you don't add required as additional validator empty string must pass

Here is phpunit test:

/** @test */
public function letterCode()
{
    $trans = new \Illuminate\Translation\Translator(
        new \Illuminate\Translation\ArrayLoader, 'en'
    );

    $regex = 'regex:/^[A-Za-z0-9\-]*$/';

    $v = new Validator($trans, ['x' => 'C14'], ['x' => $regex]);
    $this->assertTrue($v->passes());

    $v = new Validator($trans, ['x' => '3.14'], ['x' => $regex]);
    $this->assertFalse($v->passes());

    $v = new Validator($trans, ['x' => '-'], ['x' => $regex]);
    $this->assertTrue($v->passes());

    $v = new Validator($trans, ['x' => ''], ['x' => $regex]);
    $this->assertTrue($v->passes());
}

This is tested with Laravel 5.5

Answer 3

I was facing the same problem in Laravel 7.x using GraphQL Types . I needed something similar to this in a field called phone or nothig (empty string). So I did something like this:

'phone' => [
        'name' => 'phone',
        'type' => Type::string(),
        'rules' => ['regex:/^[A-Za-z0-9\-]*$/','nullable']

Here, phone is the name of the field you want to enter text into, and rules is what we define as regex, or NULL.

Hope this helps someone!