Lombok @Builder and JPA Default constructor
JavaSpringSpring Data-JpaLombokJava Problem Overview
I'm using project Lombok together with Spring Data JPA.
Is there any way to connect Lombok @Builder
with JPA default constructor?
Code:
@Entity
@Builder
class Person {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
}
As far as I know JPA needs default constructor which is overriden by @Builder
annotation. Is there any workaround for that?
This code gives me error:
org.hibernate.InstantiationException: No default constructor for entity: : app.domain.model.Person
Java Solutions
Solution 1 - Java
Updated
Based on the feedback and John's answer I have updated the answer to no longer use @Tolerate
or @Data
and instead we create accessors and mutators via @Getter
and @Setter
, create the default constructor via @NoArgsConstructor
, and finally we create the all args constructor that the builder requires via @AllArgsConstructor
.
Since you want to use the builder pattern I imagine you want to restrict visibility of the constructor and mutators methods.
To achieve this we set the visibility to package private
via the access
attribute on the @NoArgsConstructor
and @AllArgsConstructor
annotations and the value
attribute on the @Setter
annotation.
Important
Remember to properly override toString
, equals
, and hashCode
.
See the following posts by Vlad Mihalcea for details:
- the-best-way-to-implement-equals-hashcode-and-tostring-with-jpa-and-hibernate
- how-to-implement-equals-and-hashcode-using-the-jpa-entity-identifier
- hibernate-facts-equals-and-hashcode
package com.stackoverflow.SO34299054;
import static org.junit.Assert.*;
import java.util.Random;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import org.junit.Test;
import lombok.AccessLevel;
import lombok.AllArgsConstructor;
import lombok.Builder;
import lombok.Getter;
import lombok.NoArgsConstructor;
import lombok.Setter;
@SuppressWarnings("javadoc")
public class Answer {
@Entity
@Builder(toBuilder = true)
@AllArgsConstructor(access = AccessLevel.PACKAGE)
@NoArgsConstructor(access = AccessLevel.PACKAGE)
@Setter(value = AccessLevel.PACKAGE)
@Getter
public static class Person {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
/*
* IMPORTANT:
* Set toString, equals, and hashCode as described in these
* documents:
* - https://vladmihalcea.com/the-best-way-to-implement-equals-hashcode-and-tostring-with-jpa-and-hibernate/
* - https://vladmihalcea.com/how-to-implement-equals-and-hashcode-using-the-jpa-entity-identifier/
* - https://vladmihalcea.com/hibernate-facts-equals-and-hashcode/
*/
}
/**
* Test person builder.
*/
@Test
public void testPersonBuilder() {
final Long expectedId = new Random().nextLong();
final Person fromBuilder = Person.builder()
.id(expectedId)
.build();
assertEquals(expectedId, fromBuilder.getId());
}
/**
* Test person constructor.
*/
@Test
public void testPersonConstructor() {
final Long expectedId = new Random().nextLong();
final Person fromNoArgConstructor = new Person();
fromNoArgConstructor.setId(expectedId);
assertEquals(expectedId, fromNoArgConstructor.getId());
}
}
Old Version using @Tolerate
and @Data
:
Using @Tolerate
worked to allow adding a noarg constructor.
Since you want to use the builder pattern I imagine you want to control visibility of the setter methods.
The @Data
annotation makes the generated setters public
, applying @Setter(value = AccessLevel.PROTECTED)
to the fields makes them protected
.
Remember to properly override toString
, equals
, and hashCode
.
See the following posts by Vlad Mihalcea for details:
- the-best-way-to-implement-equals-hashcode-and-tostring-with-jpa-and-hibernate
- how-to-implement-equals-and-hashcode-using-the-jpa-entity-identifier
- hibernate-facts-equals-and-hashcode
package lombok.javac.handlers.stackoverflow;
import static org.junit.Assert.*;
import java.util.Random;
import javax.persistence.GenerationType;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import lombok.AccessLevel;
import lombok.Builder;
import lombok.Data;
import lombok.Setter;
import lombok.experimental.Tolerate;
import org.junit.Test;
public class So34241718 {
@Builder
@Data
public static class Person {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
@Setter(value = AccessLevel.PROTECTED)
Long id;
@Tolerate
Person() {}
/* IMPORTANT:
Override toString, equals, and hashCode as described in these
documents:
- https://vladmihalcea.com/the-best-way-to-implement-equals-hashcode-and-tostring-with-jpa-and-hibernate/
- https://vladmihalcea.com/how-to-implement-equals-and-hashcode-using-the-jpa-entity-identifier/
- https://vladmihalcea.com/hibernate-facts-equals-and-hashcode/
*/
}
@Test
public void testPersonBuilder() {
Long expectedId = new Random().nextLong();
final Person fromBuilder = Person.builder()
.id(expectedId)
.build();
assertEquals(expectedId, fromBuilder.getId());
}
@Test
public void testPersonConstructor() {
Long expectedId = new Random().nextLong();
final Person fromNoArgConstructor = new Person();
fromNoArgConstructor .setId(expectedId);
assertEquals(expectedId, fromNoArgConstructor.getId());
}
}
Solution 2 - Java
You can also solve it explicitly with @Data @Builder @NoArgsConstructor @AllArgsConstructor
combined on the class definition.
Solution 3 - Java
It seems that the annotations order is important here, using the same annotations, but different orders, you can have the code working, or not.
Here is a non working example:
@AllArgsConstructor
@Builder
@Data
@Entity
@EqualsAndHashCode
@NoArgsConstructor
@RequiredArgsConstructor
@Table
@ToString
public class Person implements Serializable {
private String name;
}
And this is a working example:
@Builder
@Data
@Entity
@EqualsAndHashCode
@AllArgsConstructor
@NoArgsConstructor
@RequiredArgsConstructor
@Table
@ToString
public class Person implements Serializable {
private String name;
}
So be sure to have the @Builder annotation at the very top position, in my case I encountered this error because I wanted to sort annotations alphabetically.
Solution 4 - Java
If the annotations lombok.Tolerate on constructor and javax.validation.constraints.NotNull on some property are used at the same time, sonarqube will mark it as a critical error: PROPERTY is marked "javax.validation.constraints.NotNull" but is not initialized in this constructor.
If the project uses SpringData with JPA, it can be solved using org.springframework.data.annotation.PersistenceConstructor (Spring annotation, not JPA!)
Then, in combination with Lombok, annotations will be like this:
@RequiredArgsConstructor(onConstructor = @__(@PersistenceConstructor))
For Lombok builder you also need to add:
@Builder
@AllArgsConstructor
Solution 5 - Java
To use the following combination
- lombok
- JPA
- CRUD
- proper
@EqualsAndHashCode
- immutability - public final fields
- no getters
- no setters
- changes via
@Builder
and@With
I used:
//Lombok & JPA
//https://stackoverflow.com/questions/34241718/lombok-builder-and-jpa-default-constructor
//Mandatory in conjunction with JPA: an equal based on fields is not desired
@lombok.EqualsAndHashCode(onlyExplicitlyIncluded = true)
//Mandatory in conjunction with JPA: force is needed to generate default values for final fields, that will be overriden by JPA
@lombok.NoArgsConstructor(access = AccessLevel.PRIVATE, force = true)
//Hides the constructor to force usage of the Builder.
@lombok.AllArgsConstructor(access = AccessLevel.PRIVATE)
@lombok.ToString
//Good to just modify some values
@lombok.With
//Mandatory in conjunction with JPA: Some suggest that the Builder should be above Entity - https://stackoverflow.com/a/52048267/99248
//Good to be used to modify all values
@lombok.Builder(toBuilder = true)
//final fields needed for imutability, the default access to public - since are final is safe
@lombok.experimental.FieldDefaults(makeFinal = true, level = AccessLevel.PUBLIC)
//no getters and setters
@lombok.Getter(value = AccessLevel.NONE)
@lombok.Setter(value = AccessLevel.NONE)
//JPA
@javax.persistence.Entity
@javax.persistence.Table(name = "PERSON_WITH_MOTTO")
//jpa should use field access
@javax.persistence.Access(AccessType.FIELD)
public class Person {
@javax.persistence.Id
@javax.persistence.GeneratedValue
//Used also automatically as JPA
@lombok.EqualsAndHashCode.Include
Long id;
String name;
String motto;
}
Solution 6 - Java
i solved this using all these annotations:
@Data
@Builder
@AllArgsConstructor(access = AccessLevel.PACKAGE)
@NoArgsConstructor(access = AccessLevel.PACKAGE)
Solution 7 - Java
Using @NoArgsConstructor
and @AllArgsContructor
will help solve the issue of having a default constructor with @Builder
.
e.g
@Entity
@Builder
@NoArgsConstructor
@AllArgsContructor
class Person {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
}
This is because @Builder
requires all argument constructor and specifying only a default constructor will cause an issue.
Here is nore explaination: https://github.com/rzwitserloot/lombok/issues/1389#issuecomment-369404719
Solution 8 - Java
Jeff's answer works fine however, @Builder does not support self-reference relationships yet.
Check this question for more details: