Laravel - How to add If in Request?

i have a section in my website with a search google maps api.

now i have this: when i enter to domain.com/fields?address_latitude=-34.5396425&address_longitude=-58.705582&dif=1 it show all places arround in 1km... It work perfect.

public function index(Request $request) {

        if ($request)
        {
            $query=trim($request->get('address_latitude'));
            $query2=trim($request->get('address_longitude'));
            $query3=trim($request->get('dif'));

            $latitude       =       $query;
            $longitude      =       $query2;
            $dif = $query3;
    
            $shops          =       DB::table("shops");
    
            $shops          =       $shops->select("*", DB::raw("6371 * acos(cos(radians(" . $latitude . "))
                                * cos(radians(latitude)) * cos(radians(longitude) - radians(" . $longitude . "))
                                + sin(radians(" .$latitude. ")) * sin(radians(latitude))) AS distance"));
            $shops          =       $shops->having('distance', '<', $dif);
            $shops          =       $shops->orderBy('distance', 'asc');
    
            $shops          =       $shops->get();

            return view('land.fields',["shops"=>$shops,"address_latitude"=>$query,"address_longitude"=>$query2,"dif"=>$query3]);
        }

    }

but i need apply a IF in case of i enter in domain.com/fields i need here display all my places... i have the code of this... but i have problem to make the "IF"

Any can help me please?