I'm not an ajax expert but, the syntax for your data differs from mine, the following worked for me in my view data was name: value combo.
I also needed to pass the csrt_token
var token = "{{csrf_token()}}";
var todo_id = $('#id_show').val();
var myurl = "{{url('updatetodo')}}" +"/"+ todo_id;
$.ajax({
type: 'PUT',
url: myurl,
dataType: 'JSON',
data: {
'_token': token,
'_method': 'PUT',
'id' : todo_id,
'due': $('#due_show').val(),
'assignedto': $('#assignedto_show').val(),
'description': $('#description_show').val(),
'notes': $('#notes_show').val(),
'status': $('#status_show').val()
},
In my controller
public function updateajax(Request $request, $id)
{
$this->validate($request, [
'description' => 'required',
'notes' => 'required',
'status' => 'required',
'due' => 'required'
]);
$requestData = $request->all();