Requst data(post) not bind to a POJO in spring

Question

I need to map the form data into a pojo, so ii set the POJO as a method parameter. So then request data should bind to the pojo. But it not working. I am using spring 4.2.3.RELEASE . This is the my code

PersonDto class

public class PersonDto {

private int userId;
private String userName;

public int getUserId() {
    return userId;
}

public void setUserId(int userId) {
    this.userId = userId;
}

public String getUserName() {
    return userName;
}

public void setUserName(String userName) {
    this.userName = userName;
}
}

UserController class

@Controller()
@RequestMapping("/u")
public class UserController {

@ResponseBody
@RequestMapping(value = "/add",method = RequestMethod.POST)
public String addUser(PersonDto dto){
    System.out.println("Name : "+dto.getUserName());
    return ""+dto.getUserName();
}

@RequestMapping("/home")
public String userHome(){
    System.out.println("UserDetailsController Index");
    return "user-home";
}
}

in here home request mapping is working. But when i send post request to /add then PersonDto is empty. This is how i send request What is the reason for this?

Answer 1

您需要在方法参数中使用@RequestBody注释PersonDto dto，以指示它应绑定到请求主体：

public String addUser(@RequestBody PersonDto dto){

Answer 2

try this options:

1. Use @RequestBody in POST method.

2. include maven dependency for jackson

   com.fasterxml.jackson.databind.ObjectMapper

Answer 3

Try to mark your method parameter with @ModelAttribute annotation:

@ResponseBody
@RequestMapping(value = "/add",method = RequestMethod.POST)
public String addUser(@ModelAttribute("dto") PersonDto dto){
    System.out.println("Name : "+dto.getUserName());
    return ""+dto.getUserName();
}

Note, that you can specify name of model attribute. If you use <spring:form> tag check you form modelAttribute attribute:

<form:form method="POST" action="/someaction" modelAttribute="dto">
   ...
</form:form>

Answer 4

I might be pretty late to the party, but if this issue is not yet resolved (since I don't see any accepted answer), this answer may help. I had a similar issue and realised that I had not added a constructor wherein all the parameters passed in request body could be set. So perhaps adding the following constructor:

public PersonDto(int userId, String userName){
     this.userId=userId;
     this.userName=userName;
}

Please let me know if this works for you. If something else already did, please share your answer since it was quite a task for me to realise my silly error.