Save Nested POJO class Objects using hibernate

Question

Class1:

int field2
Class2 field1

Class2:

Class3 field3

Class3:

String field4
String field5

Class1 domain class:

@Table(name = "class1_details")
@Entity
public class Class1Details {
  @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "id")
    private long id;
    
    @Column(name = "class2_fields")
    private Class2 fields;
  
     // respective getters and setters

}

I am using springboot. I am extending JPARepository for my repo interface. I want to save class1 in db. I am getting below exception:

org.springframework.orm.jpa.JpaSystemException: could not serialize; nested exception is org.hibernate.type.SerializationException: could not serialize ...

Caused by: org.hibernate.type.SerializationException: could not serialize ....

Caused by: java.io.NotSerializableException: com.model.Class3 ...

Tried @ElementCollection but of no use. Please help with this.

Got it. Now another exception.. Caused by: org.postgresql.util.PSQLException: ERROR: null value in column "class3_id" violates not-null constraint I havent declared any class3_id in class3. Do i need to create domain classes (@entity class) for class2 and class3 as well? — Forece85
– Forece85, Commented Aug 13, 2018 at 12:56

Cepr0 · Accepted Answer · 2018-08-13 13:44:04Z

0

You should make nested classes @Embeddable:

@Entity
@Table(name = "my_entities")
public class MyEntity {
    //...

    private MyData data;
}

@Embeddable
public class MyData {
    private String value;
}

Then Hibernate will deal with the following table:

create table my_entities (
  -- MyEntity stuff
  --
  value varchar(255)
);

Another an interesting approach is storing nested class in DB as JSON, see my related answer...

edited Aug 13, 2018 at 13:44

answered Aug 13, 2018 at 13:37

Cepr0

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Save Nested POJO class Objects using hibernate

Class1:

Class2:

Class3:

Class1 domain class:

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Class3:

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