You can bind form parameters to a domain model object even if the domain model object does not have setters. Just add a @ControllerAdvice class with an @InitBinder method that configures your application to field binding via the initDirectFieldAccess() method

package boottests.controllers;

import org.springframework.web.bind.WebDataBinder;
import org.springframework.web.bind.annotation.*;

@ControllerAdvice
class BindingControllerAdvice {
 
 @InitBinder
 void initBinder(WebDataBinder binder) {
 binder.initDirectFieldAccess();
 }
}

Here’s how my domain model looks like:

package boottests;

public class Person {
 
 private final String firstname;
 private final String lastname;
 
 public Person(String firstname, String lastname) {
 this.firstname = firstname;
 this.lastname = lastname;
 }
 
 @Override
 public String toString() {
 return firstname + " " + lastname;
 }
}

And here’s my Controller:

package boottests.controllers;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.*;

import boottests.Person;

@Controller @RequestMapping("/person")
class PersonController {
 
 @GetMapping
 String postForm(Person person) {
 System.out.println("YYY " + person + " YYY");
 return "/";
 }
}

And of course, my form, on index.html:

<form action="person" > 
Lastname: <input type="text" name="lastname"/> <br/> 
Firstname: <input type="text" name="firstname"/> <br/> 
<input type="submit" value="Submit"/> 
</form>

If you run this on Spring Boot, you’ll see that the form parameters were correctly bound to the fields of the domain model.