laravel请求将输入作为具有空值的数组键名返回

Question

I have a form that sends a request through Ajax in laravel
This snippet from my controller returns null

use Illuminate\Http\Request;
class StatusController extends Controller {
  public function postStatus(Request $request) {
    if ($request->ajax()) {
      dd($request->input('statusBody'));  

This however returns an array with statusBody as a key name with null value

use Illuminate\Http\Request;
class StatusController extends Controller {
  public function postStatus(Request $request) {
    if ($request->ajax()) {
      dd($request->input());  

This is the returned result

array:1 [▼
  "This_is_a_sample_status" => null
]  

And this finally returns the correct value

use Illuminate\Http\Request;
class StatusController extends Controller {
  public function postStatus(Request $request) {
    if ($request->ajax()) {
      $val = $request->input('statusBody');
      dd(array_search($val, $request->all()));  

My question is: Why does this happen?
Why doesn't $request->input('name') returns a value as expected?
UPDATE:
This is also the Ajax function which successfully logs the wanted result to the console

var statusBody = $('#statusBody').val();
      $.ajax({
        type: "POST",
        url: 'status',
        data: statusBody,
        success: function(data){
          console.log(statusBody);
        }
      });

Answer 1

I tried to reproduce the problem in a fresh laravel app where I found out what's wrong.
data parameter in the Ajax function expects a dataString like so

var statusBody = $('#status').val();
      var dataString = "status="+statusBody;
      $.ajax({
        type: "POST",
        url: 'status',
        data: dataString
      });

Thanks to Antonis to point out the Ajax call