Binding the select option list - spring-boot

Question

I am currently unsure on how should I be doing this. When the method = RequestMethod.POST, how should I bind the select picker to my object.
This is part of my form
<form th:action="#{/incidentDetail/update}" method="post" id="incidentDetailForm">
<div class="form-row">
<div class="form-group col-md-6">
<label for="location">Name</label> <input class="form-control"
type="text" name="ioName" id="ioName" th:value="${incident.ioName}" />
</div>
<div class="form-group col-md-3">
<label for="location" class="cols-sm-2 control-label">Preparation
By</label><span class="bg-danger pull-right"></span>
<div class="cols-sm-10">
<div class="input-group">
<span class="input-group-addon"><i class="fa fa-reorder fa"
aria-hidden="true"></i></span> <select class="form-control selectpicker"
th:object="${incident}" th:field="*{incidentPreparationBy}"
id="incidentPreparationBy" name="incidentPreparationBy"
roleId="incidentPreparationBy">
<option th:each="user: ${userList}" th:value="${incident.incidentPreparationBy}"
th:text="${user.name}"></option>
</select>
</div>
</div>
</div>
</form>
My controller
#RequestMapping(value = "/update", method = RequestMethod.POST)
public String registerIncidentPost(#ModelAttribute("incident") Incident incident, HttpServletRequest request)
throws Exception {
incidentService.save(incident);
return "redirect:/incidentDetail?id=" + incident.getId();
}
Part of Incident Entity
#ManyToOne
#JoinColumn(name = "user_id_preparation_by")
private User incidentPreparationBy;

Answer 1

You can acces the select by adding:
#RequestParam("incidentPreparationBy") String option as a method argument
to your controller method.
This way the string "option" will contain the selected value.
Like this:
#RequestMapping(value = "/update", method = RequestMethod.POST)
public String registerIncidentPost(#ModelAttribute("incident") Incident incident,
#RequestParam("incidentPreparationBy") String option, HttpServletRequest request)
throws Exception {
String incidentPrepartionBy = option; //incidentPrepartionBy will give you the selected value now.
incidentService.save(incident);
return "redirect:/incidentDetail?id=" + incident.getId();
}