Handling a oneToMany relationship in Spring boot JPA - spring

Question

In my database I have a user who can have multiple email addresses. An email address can have only one user. I have following two tables in my database to handle this.
CREATE TABLE IF NOT EXISTS w4a_user (
id INTEGER NOT NULL AUTO_INCREMENT,
login_id VARCHAR(100) NOT NULL UNIQUE,
first_name VARCHAR(100),
last_name VARCHAR(100),
division INTEGER NOT NULL,
created_date TIMESTAMP NOT NULL,
last_active DATE,
PRIMARY KEY (id),
FOREIGN KEY (login_id) REFERENCES w4a_authentication_data (login_id) ON DELETE RESTRICT,
FOREIGN KEY (division) REFERENCES w4a_division (id) ON DELETE RESTRICT
);
CREATE TABLE IF NOT EXISTS w4a_email_address(
email_address VARCHAR(100) NOT NULL,
user_id INTEGER NOT NULL,
is_confirmed BOOLEAN NOT NULL DEFAULT FALSE,
PRIMARY KEY (email_address),
FOREIGN KEY (user_id) REFERENCES w4a_user (id) ON DELETE CASCADE
);
In my Spring boot application, I have following entity classes to handle this.
User.java
#Entity
#Table(name = "w4a_user")
public class User {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column(name = "id")
private int id;
#Column(name = "first_name")
#Size(max = 100, message = GlobalConstants.ErrorMessageConstants.ERROR_FIRST_NAME_LENGTH_EXCEEDED)
private String firstName;
#Column(name = "last_name")
#Size(max = 100, message = GlobalConstants.ErrorMessageConstants.ERROR_LAST_NAME_LENGTH_EXCEEDED)
private String lastName;
#Column(name = "created_date")
private Date createdDate;
#Column(name = "last_active")
private Date lastActive;
#ManyToOne
#JoinColumn(name = "division", referencedColumnName = "id")
private Division division;
#OneToMany(mappedBy = "userId", cascade = CascadeType.ALL, orphanRemoval = true)
#Size(min = 1)
private List<ContactNumber> contactNumberList;
#OneToMany(mappedBy = "userId", cascade = CascadeType.ALL, orphanRemoval = true)
#Size(min = 1)
private List<EmailAddress> emailAddresses;
.
.
}
EmailAddress.java
#Entity
#Table(name = "w4a_email_address")
public class EmailAddress {
#Id
#Column(name = "email_address")
#Email(message = GlobalConstants.ErrorMessageConstants.ERROR_EMAIL_INCORRECT_FORMAT,
regexp = GlobalConstants.RegexList.EMAIL_REGEX)
#Size(max = 100, message = GlobalConstants.ErrorMessageConstants.ERROR_EMAIL_LENGTH_EXCEEDED)
private String emailAddress;
#ManyToOne
#JoinColumn(name = "user_id", referencedColumnName = "id")
private User userId;
#Column(name = "is_confirmed")
private Boolean isConfirmed;
.
.
}
I use following method to persist entitites to my database.
#PersistenceContext
private EntityManager em;
#Override
public T createEntity(T entity) {
this.em.unwrap(Session.class).save(entity);
return entity;
}
I set email address list in the user entity and perform above method to create a new user.
The issue I have is when adding a user with an email address already used by an existing user. In this case, the database entry for the email address gets updated with the id of the new user. Instead I want to give an error saying the email address is already in use. What is the best way of handling this?