Spring JPA - studiofu/brain GitHub Wiki

// contain "-"
@GenericGenerator(name = "uuid", strategy = "uuid2")
@Id
@GeneratedValue(generator="uuid")

// contain "-"
@GenericGenerator(name="uuid2", strategy = "org.hibernate.id.UUIDGenerator")
@Id
@GeneratedValue(generator="uuid2")

// https://www.jianshu.com/p/1fd8330404cc
@GenericGenerator(name="jpa-uuid", strategy="uuid")
@Id
@GeneratedValue(generator="uuid2")

@Entity
public class Person {

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

    @OneToMany(mappedBy="person", cascade=CascadeType.ALL)
    private List<Address> addresses;
}

@Entity
public class Address {

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

    @ManyToOne
    @JoinColumn(name="ADDRESS_FK")
    @Column(insertable=false, updatable=false)
    private Person person;
}

You would do that when the responsibility of creating/updating the 
related entity in question isn't in the current entity. E.g. you have a Person and an Address. 
You'd like to add insertable=false, updatable=false to the @OneToMany relationship 
with the Person entity in the Address entity, simply because it's not the responsibility 
of the Address entity to create or update a Person. It's the other way round.

Table User (address_id is used in table user and id is in the table Address)
    @OneToOne(cascade = CascadeType.ALL)
    @JoinColumn(name = "address_id", referencedColumnName = "id")
    private Address address;

Table Address
    @OneToOne(mappedBy = "address")
    private User user;

Table User
    @OneToOne(mappedBy = "user", cascade = CascadeType.ALL)
    private Address address;
Table Address
    @OneToOne
    @MapsId
    private User user;

table employee
    @OneToOne(cascade = CascadeType.ALL)
    @JoinTable(name = "emp_workstation", 
      joinColumns = 
        { @JoinColumn(name = "employee_id", referencedColumnName = "id") },
      inverseJoinColumns = 
        { @JoinColumn(name = "workstation_id", referencedColumnName = "id") })
    private WorkStation workStation;
table workstation
    @OneToOne(mappedBy = "workStation")
    private Employee employee;

Table Cart
    @OneToMany(mappedBy="cart")
    private Set<Items> items;
Table Item
    @ManyToOne
    @JoinColumn(name="cart_id", nullable=false)
    private Cart cart;

table student
    @ManyToMany
    @JoinTable(
      name = "course_like", 
      joinColumns = @JoinColumn(name = "student_id"), 
      inverseJoinColumns = @JoinColumn(name = "course_id"))
    Set<Course> likedCourses;
table course
    @ManyToMany(mappedBy = "likedCourses")
    Set<Student> likes;

@Embeddable
class CourseRatingKey implements Serializable {
 
    @Column(name = "student_id")
    Long studentId;
 
    @Column(name = "course_id")
    Long courseId;
 
    // standard constructors, getters, and setters
    // hashcode and equals implementation
}

@Entity
class CourseRating {
 
    @EmbeddedId
    CourseRatingKey id;
 
    @ManyToOne
    @MapsId("student_id")
    @JoinColumn(name = "student_id")
    Student student;
 
    @ManyToOne
    @MapsId("course_id")
    @JoinColumn(name = "course_id")
    Course course;
 
    int rating;
     
    // standard constructors, getters, and setters
}

table student
    @OneToMany(mappedBy = "student")
    Set<CourseRegistration> registrations;
table course
    @OneToMany(mappedBy = "courses")
    Set<CourseRegistration> registrations;
table course_registration
    @ManyToOne
    @JoinColumn(name = "student_id")
    Student student;
 
    @ManyToOne
    @JoinColumn(name = "course_id")
    Course course;