Laravel validation for file not empty but less then 1 kb?

How to validate that uploaded file is not empty in case it is less then 1kb?

$request->validate([
  'file' => [
    'required',
    'file',
    'extensions:zip',
    'max:1024',
    'min:1'
  ]
]);

The validation rule will return error "The file field must be at least 1 kilobytes" on file size 600 bytes.

Does a built in validation exist for file size !=== null?

The problem is that Laravel's min and max rules for files are based on kilobytes, not bytes. So if you set min:1, it actually means the file needs to be at least 1024 bytes. A file that's only 600 bytes will not pass this check.

There's no built-in rule called "min_bytes," but you don't need to create a custom rule class for this.
The easiest way to fix it right away is by using a Closure.

$request->validate([
    'file' => [
        'required',
        'file',
        'extensions:zip',
        'max:1024', // 1MB
        // Custom closure to check file size in bytes
        function ($attribute, $value, $fail) {
            // $value is an instance of Illuminate\Http\UploadedFile
            if ($value->getSize() < 1) {
                 $fail("The {$attribute} cannot be empty.");
            }
        },
    ],
]);

The closure gives you access to the actual UploadedFile object. The getSize() method returns the size in bytes, allowing you to validate that it is truly not empty ( > 0 bytes) without forcing it to be a whole kilobyte.