Spring MVC: Binding complex Objects to UI

Question

I have my User Object which I am trying to bind to UI with spring MVC. User Object has another object Address in it.

public class User {
    String firstName;
          


        

Answer 1

To get your Address object back, you will need to list out each of the individual properties: for ex:

<form:hidden path="user.address.street" />
<form:hidden path="user.address.country" />

and so on.

Now, the object that you bind to the UI is the object that you passed from your controller. I am assuming that When the form gets submitted you want to get the User object back as a @ModelAttribute. In that case, you have two options: the first is that you will need to list out all the properties of your User object on the client-side (either as hidden objects or as visible form-elements).

The second options is: you only display the required properties on the client-side, and rather than listing all the other propeties as hidden fields, you only keep the id of your User instance as a hidden field. Now, when you receive this @ModelAttribute upon form-submission, you can load the whole object from the database using the id and set the updated properties on it before calling update.

for ex:

@RequestMapping("updateUser.do")
public String updateUser(@ModelAttribute User user, ... /* rest of the args */) {
    // ... some other code
    User existingUser = userService.findById(user.getId());
    existingUser.setFirstName(user.getFirstName());
    existingUser.setLasstName(user.getLastName());

    userService.update(existingUser);
    // ... rest of the code
}

There is no way that you can work only on the required-properties on the client-side, and merge it with that same existing object.