Spring Boot — JPA Entity Relationships

In this post, I’ll implement how to work with relationships between entities in Spring Data REST with JPA.

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Generally, the entity classes are treated as relational tables, therefore the relationships between Entity classes are as follows:

@OneToOne Relationship

One to One relationship is a condition where data in a table only has a relationship to one data in another table. For example,

The diagram explains One-To-One relationship as follows:

a simple word to express this is:

One employee only has one account and vice versa.

• Employee

@Entity
@Table(name = "employee")
public class Employee {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private int id;

    private String name;
    private String email;

// constructors, getters, setters
}

• Account

@Entity
@Table(name = "account")
public class Account {

    @Id
    private int id;

    private String password;

    @OneToOne
    @JoinColumn(name = "id", referencedColumnName = "id")
    private Employee employee;
// constructors, getters, setters
}

@OneToMany and @ManyToOne…