Dynamically created Dropdown list does not return a value - spring-mvc

Question

I create my dropdown based on values from an enum, then try to return the value by using the th:value="${parameterName}" like for other fields, but the return value is null.
Controller get method:
#GetMapping("/createorupdatebusvehicle/{id}")
public String createBusVehicleDisplay(Model model, #PathVariable(value = "id") long id, HttpServletResponse response) throws IOException {
BusVehicle busVehicle = busVehicleRepository.findById(id).get();
if(busVehicle == null){
response.sendRedirect("/createorupdatebusvehicle");
return null;
}
model.addAttribute("busVehicleId", id);
model.addAttribute("busVehicleColor", busVehicle.getColor().toString());
model.addAttribute("busVehicleType", busVehicle.getType().toString());
// all attributes are set
return "createOrUpdateBusVehicle";
}
Page view:
<form action="#" th:action="#{/createorupdatebusvehicle}" method="post">
<input type="hidden" name="busVehicleId" th:value="${busVehicleId}" />
<p>Plate number: <input type="text" name="busVehiclePlateNumber" th:value="${busVehiclePlateNumber}" /></p>
<p>Passenger capacity: <input type="text" name="busVehiclePassengerCapacity" th:value="${busVehiclePassengerCapacity}" /></p>
//== Here are the selects ==
<select name="color">
<option th:each="colorOpt : ${T(com.grazzini.model.BusVehicleColor).values()}"
th:value="${busVehicleColor}" th:text="${colorOpt}" th:selected="${busVehicleColor} == colorOpt"></option>
</select>
<select name="type">
<option th:each="typeOpt : ${T(com.grazzini.model.BusVehicleType).values()}"
th:value="${busVehicleType}" th:text="${typeOpt}" th:selected="${busVehicleType} == typeOpt"></option>
</select>
Then get the selected value back in the controller:
#PostMapping("/createorupdatebusvehicle")
public String checkAndCreateBusVehicle (HttpServletRequest request, HttpServletResponse response) throws IOException {
String busVehicleId = request.getParameter("busVehicleId");
//...
String busVehicleColor = request.getParameter("busVehicleColor"); //null
String busVehicleType = request.getParameter("busVehicleType"); //null
/// the rest
Color and Type are enums. All other requests return the correct value, for a text field for example. Any idea why this one behave differently?

Answer 1

You have name="..." on the fields that are working. You need to add name="busVehicleColor" and name="busVehicleType" on your respective <select /> tags..