custom date validation

use a rule closure described here for your date_end: https://laravel.com/docs/5.8/validation#using-closures

You can use carbon and subtract the 2 dates within the closure and return $fail($attribute.' is greater than 5 days'); or whatever you want the error message to be if it fails.

I think that can do the trick. something like this, just that i am unsure how to add that to the existing date_end validation rules, as in the example it is done different syntax.

$validatedData = $request->validate([
            'date_start' => 'required|date',
            'date_end' => 'required|date|after_or_equal:date_start',
            function ($attribute, $value, $fail){
                $start = Carbon::parse($request->get('date_start'));
                $end = Carbon::parse($request->get('date_end'));
                if($end->diffInDays($start)>1){
                    $fail($attribute.' date range is bigger than 1 day.');
                }
            }
        ]);

Changed it to this:

$validatedData = $request->validate([
            'date_start' => 'required|date',
            'date_end' => ['required','date','after_or_equal:date_start',
                function ($attribute, $value, $fail){
                $start = Carbon::parse($request->get('date_start'));
                $end = Carbon::parse($value);
                if($end->diffInDays($start)>1){
                    $fail($attribute.' date range is bigger than 1 day.');
                }
            }],
            
        ]);

the problem is that i get an eror since $request->get('date_start' does not exist

You need to pass $request to the closure, and just use $request->date_start instead of $request->get(), unless it's a GET request.

function ($attribute, $value, $fail) use ($request) {
    $start = Carbon::parse($request->date_start);

Thanks! didn't know about that syntax to pass on a variable.