Form validation in spring with thymeleaf - spring

Question

I'm skilling in form validation with spring boot and thymeleaf and i have problem: i can't do validation in form with two #ModelAttribute fields. The example like form validation om spring official site works correctly, but when I added two #model Attribute in post i get only error at webpage and no hints at form like in spring example.
Controller class:
#Controller
public class MyController {
#Autowired
InstructorRepository instructorRepository;
#Autowired
DetailRepository detailRepository;
#GetMapping("/index")
public String mainController(){
return "index";
}
#GetMapping("/add")
public String addInstructorForm(Model model){
model.addAttribute("instructor", new Instructor());
model.addAttribute("detail", new InstructorDetail());
return "addInstructor";
}
#PostMapping("/add")
public String submitForm(#Valid #ModelAttribute Instructor instructor, #ModelAttribute InstructorDetail instructorDetail, BindingResult bindingResult1){
/* if (bindingResult.hasErrors()) {
return "instructorsList";
}
instructor.setInstructorDetail(instructorDetail);
instructorRepository.save(instructor);*/
if (bindingResult1.hasErrors()) {
return "addInstructor";
}
return "redirect:/instructorsList";
}
#GetMapping("/instructorsList")
public String getList(Model model){
Map map = new HashMap<>();
List list = new ArrayList<Instructor>();
list = instructorRepository.findAll();
List resultList = new ArrayList();
for (int i = 0; i < list.size(); i++) {
Instructor instructor = (Instructor)list.get(i);
InstructorDetail detail = detailRepository.getInstructorDetailById(instructor.getId());
InstructorAndDetail iid = new InstructorAndDetail(instructor, detail);
resultList.add(iid);
}
model.addAttribute("instructors", resultList);
return "instructorsList";
}
}
html form snippet:
<form action="#" data-th-action="#{/add}" data-th-object="${instructor}" method="post">
<div class="form-group">
<label for="1">First name</label>
<input class="form-control" id="1" type="text" data-th-field="${instructor.firstName}" placeholder="John"/>
<div data-th-if="${#fields.hasErrors('firstName')}" data-th-errors="${instructor.firstName}">name error</div>
</div>

Answer 1

There was next problem: then I add entity to thymeleaf form I passed only 2 fields (or one field after), but there was 3 fields with
#NotNull
#Size(min=2, max=30)
So when I commented them in my code the single field validation begin to work :).
If you stucked at the same problem check that all you fields in class that marked #Valid annotation are mirrored in your form.
(or have default valid values? UPD: dont work with valid defaults if they have no form mirroring)