Spring Boot @SessionAttributes not working

Question

I have a Controller class in a SpringBoot project to have a login functionality. When I enter username and password and press submit, it will call LoginController with method="POST". I want that when I use the Model to add attribute "customer", that "customer" attribute will be added into session through @SessionAttributes("customer") too. Instead it return error

Here is the error

Expected session attribute 'customer'
org.springframework.web.HttpSessionRequiredException: Expected session attribute 'customer'

Here is my code

@Controller
@SessionAttributes("customer")
public class LoginController {
    
    @Autowired
    CustomerService customService;
    
    @RequestMapping(method=RequestMethod.GET,value="/login")
    public String login() {
        
        return "login";
    }
    
    @RequestMapping(method=RequestMethod.POST,value="/login")
    public String submitLoginForm(@ModelAttribute Customer customer, Model model) {
                
        model.addAttribute("customer", customService.getCustomer(customer.getUsername(), customer.getPassword()));
                
        return "redirect:/";
    }
    
}```

Answer 1

You've to annoate the getCustomer method with the @ModelAttribute("customer")

For eg:

@Service
public class CustomerService {

    @ModelAttribute("customer")
    public Customer getCustomer(String username, String password) {
        return new Customer(username, password);
    }

}

Model Object

public class Customer {

    private String username;
    private String password;

    public Customer(String username, String password) {
        this.username = username;
        this.password = password;
    }

    public String getUsername() {
        return username;
    }

    public String getPassword() {
        return password;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public void setPassword(String password) {
        this.password = password;
    }

}

Controller

@Controller
@SessionAttributes("customer")
public class LoginController {
    
    @Autowired
    CustomerService customService;
    
    @RequestMapping(method=RequestMethod.GET,value="/login")
    public String login() {    
        return "login";
    }
    
    @RequestMapping(method=RequestMethod.POST,value="/login")
    public String submitLoginForm(Customer customer, Model model, HttpServletRequest request) {            
        model.addAttribute("customer", customService.getCustomer(customer.getUsername(), customer.getPassword()));
        return "redirect:/";
    }
     
}