Please explain about insertable=false and updatable=false in reference to the JPA @Column annotation

user_240337 0
Viewed 189250

If a field is annotated insertable=false, updatable=false, doesn't it mean that you cannot insert value nor change the existing value? Why would you want to do that?

@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;
}
eclipselink jakarta-ee jpa java
8 Answers
user_154013000

According to Javax's persistence documentation:

Whether the column is included in SQL UPDATE statements generated by the persistence provider.

It would be best to understand from the official documentation here.

user_9136010

Another reason could be that your attribute is mapper to a column of a view (Example, your hibernate entity is the fusion of a table and a view). So it does not make sens that your column can be inserted (nor updated).

@Entity
@Table(name = "THE_VIEW")
@SecondaryTable(name = "THE_TABLE", pkJoinColumns = @PrimaryKeyJoinColumn(name = "THE_ID"))
public class MyEntity {

    @Id
    @Column(name = "THE_ID")
    private Integer id;

    @Column(name = "VIEW_COLUMN", updatable = false, insertable = false)
    private String viewColumn

    @Column(name = "TABLE_COLUMN", table = "THE_TABLE")
    private String tableColumn;

(I don't talk about updatable views here)

user_15461370

Adding to the previous answers, a common use of insertable=false, updatable=false is to save redundant database queries, thereby improving performance.

Imagine having a Client class, which has a Parent entity. If you just want to check if a Client has a Parent, you simply need to check for the presence of value in its parent_id column. There is no need to ask Hibernate to fetch the Parent entity, with possibly all of its other associations, leading to additional number of queries:

public class Client {
    @ManyToOne(cascade = {CascadeType.MERGE, CascadeType.PERSIST}, fetch = FetchType.LAZY)
    @JoinColumn(name = "parent_id")
    private Parent parent;

    @Column(name = "parent_id", insertable = false, updatable = false)
    private UUID parentId;
}

With the setup above, the parentId field will simply fetch whatever value is stored in the parent_id column, which is solely edited/updated by the Parent entity.

user_118125180
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