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Lombok @Builder and JPA Default constructor

I'm using project Lombok together with Spring Data JPA.
Is there any way to connect Lombok @Builder with JPA default constructor?

@Builder

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?

@Builder

This code gives me error:
org.hibernate.InstantiationException: No default constructor for entity: : app.domain.model.Person

org.hibernate.InstantiationException: No default constructor for entity: : app.domain.model.Person

@NoArgsConstructor

@Builder

4 Answers
4

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.

@Tolerate

@Data

@Getter

@Setter

@NoArgsConstructor

@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 @Setterannotation.

package private

access

@NoArgsConstructor

@AllArgsConstructor

value

@Setter

Important

Remember to properly override toString, equals, and hashCode.
See the following posts by Vlad Mihalcea for details:

toString

equals

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:

@Tolerate

@Data

Using @Tolerate worked to allow adding a noarg constructor.

@Tolerate

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.

@Data

public

@Setter(value = AccessLevel.PROTECTED)

protected

Remember to properly override toString, equals, and hashCode.
See the following posts by Vlad Mihalcea for details:

toString

equals

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());




@Tolerate

@Data

@Data

@Data

You can also solve it explicit with @Builder @NoArgsConstructor @AllArgsConstructor combined on the class definition.

@Builder @NoArgsConstructor @AllArgsConstructor

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


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.

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