th:if="${#fields.hasErrors()}" causes Exception evaluating SpringEL expression - spring

Question

I'm trying to do validation on 1 field of the form as you guys can see:
<div id ="EditModal" class="modal fade" role="dialog">
<form class="modal-dialog" th:action="#{/Edit}" th:object="${person1}" method="POST">
<div class="modal-content">
<div class="modal-header">
<button type="button" class="close" data-dismiss="modal">×</button>
</div>
<div class="modal-body">
<input type="hidden" id="edit-modal-person-id" name="id" value=""/>
<input type="text" placeholder="Name" id="edit-modal-person-name" name="name"/>
<p th:if="${#fields.hasErrors('name')}" th:errors="*{name}" th:class="'error'">something</p>
<div>
<a class="btn btn-default pull-right" id="PhoneNumberEdit">Edit Phone Number</a>
</div>
</div>
<div class="modal-footer">
<button type="submit" id="SubmitEdit" class="btn btn-default" >Submit</button>
<button type="button" class = "btn btn-default" data-dismiss="modal">Cancel</button>
</div>
</div>
</form>
</div>
the attribute th:if="${#fields.hasErrors('name')}" always causes the 500 error for me.
my controller:
#RequestMapping(value = "/Edit", method = RequestMethod.POST)
public String editPerson(#Valid #ModelAttribute(value="person1") PersonRequest person, BindingResult result) {
if(result.hasErrors()) {
return "redirect:All";
}
else {
personService.update(person.getId(), person.getName());
return "redirect:All";
}
}
my entity:
public class PersonRequest {
#NotNull
private long id;
#NotEmpty
#Name
private String name;
public long getId() {
return id;
}
public void setId(long id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public PersonRequest() {
super();
}
}
the console return this following error:
java.lang.IllegalStateException: Neither BindingResult nor plain target object for bean name 'person1' available as request attribute.
But I think that doesnt have anything to do with this because if I remove p tag it runs normally.

Answer 1

The problem is that you make a redirect, (you make a "redirect:All").
Because of the redirect, you do not pass object person1 thus the error "java.lang.IllegalStateException: Neither BindingResult nor plain target object for bean name 'person1' available as request attribute".
If you want post the code of the /all requestMapping that you have
Probably you want something like this
#RequestMapping(value = "/Edit", method = RequestMethod.POST)
public String editPerson(#Valid #ModelAttribute(value="person1") PersonRequest person, BindingResult result) {
if(result.hasErrors()) {
return "edit";//change it to the name of the html page that you want to go
}
else {
//probably here you return in the page with all the persons
personService.update(person.getId(), person.getName());
return "redirect:All";
}
}