table data filter in laravel 5.6

I have a table where I am showing all the data. Now I want to make a filter to show specific data. I want to execute this query "SELECT * FROM internal_visitors WHERE isSignIn = 1" in Laravel. But I didn't get any data.

Controller

public function index(Request $request){

    $hosts = App\Host::all();
    if($request->method('post') && $request->isSignIn!=""){
        $isSignIn  = $request->isSignIn;

        $internalVisitors =     InternalVisitor::where('isSignIn', '=', 1)->get();

        dd(internalVisitors);
    } 


    else{

        $internalVisitors = InternalVisitor::all();
    }


    return view('admin\internalVisitor', compact('hosts','internalVisitors'));
}

view:

<form action="" method="POST">
@csrf
<li>
    <button name="isSignIn" type="submit">is</button>
</li>

via Chebli Mohamed