Purpose

A simple web app to demonstrate the use of Spring MVC, Thymeleaf, Spring Boot, Bean Validation, Unit Test and persistence in HSQLDB.

User Registration Validation

The following rules are applied for validation and app behavior:

• The username field accepts alpha-numeric values only
• The username length is no less than 5 characters
• The username is not already registered
• The password has a minimum length of 8 characters and contains at least 1 number, 1 uppercase, and 1 lowercase character
• The user gets feedback when the username or the password doesn't meet the criteria
• Upon submission of a valid username and password, they are persisted to a database
• The user gets feedback that he/she has been registered

Validation Rules

@Entity
@Table(name = "person", uniqueConstraints=@UniqueConstraint(columnNames= {"userName"}))
public class PersonForm {

@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long id;

@NotNull(message = "Username is required")
@Size(min=5, message="Username length is no less than 5 characters")
@Pattern(message="Username accepts alpha-numeric values only" , regexp="^[a-zA-z0-9]*$")
private String userName;

@NotNull(message = "Password is required")
@Size(min=8, message="The password length is no less than 8 characters")
@Pattern(message="Password should contains at least 1 number, 1 uppercase, and 1 lowercase character ", regexp="^(?=.*[a-z])(?=.*[A-Z])(?=.*\\d)[a-zA-Z\\d]{8,}$")
private String password;

public Long getId() {
	return id;
}

public void setId(Long id) {
	this.id = id;
}

public String getUserName() {
	return userName;
}

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

public String getPassword() {
	return password;
}

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

@Override
public String toString() {
	return "Username is " + this.userName + " and password is " + this.password;
}

}

Controllers

@Controller
public class PersonRegistration implements WebMvcConfigurer {

@Autowired
private PersonService personService;

private static final String USER_REGISTRATION_FORM = "personForm";

@Override
public void addViewControllers(ViewControllerRegistry registry) {
    registry.addViewController("/results").setViewName("results");
}

@GetMapping("/")
public String showForm(PersonForm personForm) {
	return USER_REGISTRATION_FORM;
}

@PostMapping("/")
public String checkPersonInfo(@Valid PersonForm personForm, BindingResult bindingResult) {
	System.out.println(personForm.toString());
	if (bindingResult.hasErrors()) {
		return USER_REGISTRATION_FORM;
	}
	//Save the Username and Password in HSQLDB
	personService.add(personForm);
	
	return "redirect:/results";
}

}

Service

@Service public class PersonServiceImpl implements PersonService {

@Autowired
private PersonRepository personRepository;

public PersonServiceImpl() {
}

@Override
public void add(PersonForm person) {
	personRepository.save(person);
}

}

References

[1] How to use regular expressions to enforce password policies - https://arnhem.luminis.eu/how-to-use-regular-expressions-to-enforce-password-policies/