Programming for beginners: Spring Data JPA: @CreatedBy and @LastModifiedBy

@CreatedBy and @LastModifiedBy are auditing annotations, these are used to track who created and modified the entities.

Annotation	Description
@CreatedBy	Declares a field as the one representing the principal that created the entity containing the field.
@LastModifiedBy	Declares a field as the one representing the principal that recently modified the entity containing the field.

Step 1: Create a model class Employee and annotate it with @EntityListeners annotation.

@Entity
@Table(name = "my_employee")
@EntityListeners(AuditingEntityListener.class)
public class Employee {
    .....
    .....
}

Step 2: Define fields using @CreatedBy and @LastModifiedBy annotations.

@Entity
@Table(name = "my_employee")
@EntityListeners(AuditingEntityListener.class)
public class Employee {
    .....
    .....
    
    @CreatedBy
    private String createdBy;

    @LastModifiedBy
    private String modifiedBy;

    .....
    .....
}

Step 3: Implement 'AuditorAware' interface.

public class AuditorAwareImpl implements AuditorAware<String> {

    @Override
    public Optional<String> getCurrentAuditor() {
        return Optional.of("Hari");
    }

}

Step 4: Create AuditorAwareImpl bean.

@Bean
AuditorAware<String> auditorProvider() {
    return new AuditorAwareImpl();
}

Step 5: Annotate main application class with @EnableJpaAuditing annotation.

@SpringBootApplication
@EnableJpaAuditing
public class App {

    .....
    .....
    
}

Find the below working application.

Employee.java

package com.sample.app.model;

import java.util.Date;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.EntityListeners;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;

import org.springframework.data.annotation.CreatedBy;
import org.springframework.data.annotation.CreatedDate;
import org.springframework.data.annotation.LastModifiedBy;
import org.springframework.data.annotation.LastModifiedDate;
import org.springframework.data.jpa.domain.support.AuditingEntityListener;

@Entity
@Table(name = "my_employee")
@EntityListeners(AuditingEntityListener.class)
public class Employee {
	@Id
	@GeneratedValue(strategy = GenerationType.AUTO)
	private Integer id;

	@Column(name = "first_name")
	private String firstName;

	@Column(name = "last_name")
	private String lastName;

	@Column(name = "age")
	private Integer age;

	@Column(name = "salary")
	private Double salary;

	@CreatedDate
	@Column(name = "created_date")
	private Date createdTime;

	@LastModifiedDate
	@Column(name = "last_modified_date")
	private Date lastModifiedTime;

	@CreatedBy
	private String createdBy;

	@LastModifiedBy
	private String modifiedBy;

	public Integer getId() {
		return id;
	}

	public void setId(Integer id) {
		this.id = id;
	}

	public String getFirstName() {
		return firstName;
	}

	public void setFirstName(String firstName) {
		this.firstName = firstName;
	}

	public String getLastName() {
		return lastName;
	}

	public void setLastName(String lastName) {
		this.lastName = lastName;
	}

	public Integer getAge() {
		return age;
	}

	public void setAge(Integer age) {
		this.age = age;
	}

	public Double getSalary() {
		return salary;
	}

	public void setSalary(Double salary) {
		this.salary = salary;
	}

	public static EmployeeBuilder builder() {
		return new EmployeeBuilder();
	}

	public Date getCreatedTime() {
		return createdTime;
	}

	public void setCreatedTime(Date createdTime) {
		this.createdTime = createdTime;
	}

	public Date getLastModifiedTime() {
		return lastModifiedTime;
	}

	public void setLastModifiedTime(Date lastModifiedTime) {
		this.lastModifiedTime = lastModifiedTime;
	}

	public static class EmployeeBuilder {
		private Employee emp;

		public EmployeeBuilder() {
			emp = new Employee();
		}

		public EmployeeBuilder firstName(String firstName) {
			emp.setFirstName(firstName);
			return this;
		}

		public EmployeeBuilder lastName(String lastName) {
			emp.setLastName(lastName);
			return this;
		}

		public EmployeeBuilder age(int age) {
			emp.setAge(age);
			return this;
		}

		public EmployeeBuilder salary(double salary) {
			emp.setSalary(salary);
			return this;
		}

		public Employee build() {
			return emp;
		}
	}

	public String getCreatedBy() {
		return createdBy;
	}

	public void setCreatedBy(String createdBy) {
		this.createdBy = createdBy;
	}

	public String getModifiedBy() {
		return modifiedBy;
	}

	public void setModifiedBy(String modifiedBy) {
		this.modifiedBy = modifiedBy;
	}

	@Override
	public String toString() {
		StringBuilder builder = new StringBuilder();
		builder.append("Employee [id=").append(id).append(", firstName=").append(firstName).append(", lastName=")
				.append(lastName).append(", age=").append(age).append(", salary=").append(salary)
				.append(", createdTime=").append(createdTime).append(", lastModifiedTime=").append(lastModifiedTime)
				.append(", createdBy=").append(createdBy).append(", modifiedBy=").append(modifiedBy).append("]");
		return builder.toString();
	}

}

AuditorAwareImpl.java

package com.sample.app.model;

import java.util.Optional;

import org.springframework.data.domain.AuditorAware;

public class AuditorAwareImpl implements AuditorAware<String> {

	@Override
	public Optional<String> getCurrentAuditor() {
		return Optional.of("Hari");
	}

}

EmployeeRepository.java

package com.sample.app.repository;

import org.springframework.data.jpa.repository.JpaRepository;

import com.sample.app.model.Employee;

public interface EmployeeRepository extends JpaRepository<Employee, Integer> {

}

App.java

package com.sample.app;

import java.util.List;

import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;
import org.springframework.data.domain.AuditorAware;
import org.springframework.data.jpa.repository.config.EnableJpaAuditing;

import com.sample.app.model.AuditorAwareImpl;
import com.sample.app.model.Employee;
import com.sample.app.repository.EmployeeRepository;

@SpringBootApplication
@EnableJpaAuditing
public class App {

	public static void main(String args[]) {
		SpringApplication.run(App.class, args);
	}

	@Bean
	public CommandLineRunner demo(EmployeeRepository employeeRepository) {
		return (args) -> {
			Employee emp1 = Employee.builder().firstName("Ram").lastName("Gurram").age(32).salary(100000.23).build();
			Employee emp2 = Employee.builder().firstName("Joel").lastName("Chelli").age(43).salary(60000).build();
			Employee emp3 = Employee.builder().firstName("Gopi").lastName("Battu").age(32).salary(1000000).build();
			Employee emp4 = Employee.builder().firstName("Bomma").lastName("Srikanth").age(39).salary(60000).build();
			Employee emp5 = Employee.builder().firstName("Surendra").lastName("Sami").age(32).salary(100000.23).build();
			Employee emp6 = Employee.builder().firstName("Bhadri").lastName("Venakata RamaRao").age(32)
					.salary(100000.23).build();
			Employee emp7 = Employee.builder().firstName("Sushmithaa").lastName("Kulakarni").age(39).salary(100000.23)
					.build();

			employeeRepository.save(emp1);
			employeeRepository.save(emp2);
			employeeRepository.save(emp3);
			employeeRepository.save(emp4);
			employeeRepository.save(emp5);
			employeeRepository.save(emp6);
			employeeRepository.save(emp7);

			List<Employee> emps = employeeRepository.findAll();

			for (Employee emp : emps) {
				System.out.println(emp);
			}

		};
	}

	@Bean
	AuditorAware<String> auditorProvider() {
		return new AuditorAwareImpl();
	}

}

Create application.properties file under src/main/resources folder.

application.properties

logging.level.root=WARN
logging.level.org.hibernate=ERROR

## H2 specific properties
spring.h2.console.enabled=true
spring.h2.console.path=/h2

spring.datasource.url=jdbc:h2:file:~/db/myOrg.db;DB_CLOSE_ON_EXIT=FALSE;DB_CLOSE_DELAY=-1;

spring.datasource.username=krishna
spring.datasource.password=password123

spring.datasource.driverClassName=org.h2.Driver

## JPA specific properties
# Creates the schema, destroying previous data.
spring.jpa.hibernate.ddl-auto=create

spring.jpa.database-platform=org.hibernate.dialect.H2Dialect

#spring.jpa.show-sql=true
#spring.jpa.properties.hibernate.format_sql=true

## Database connection pooling properties
# Number of ms to wait before throwing an exception if no connection is available.
spring.datasource.max-wait=10000

# Maximum number of active connections that can be allocated from this pool at the same time.
spring.datasource.tomcat.max-active=10
spring.datasource.tomcat.max-idle=5
spring.datasource.tomcat.min-idle=3

pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<groupId>springJPA</groupId>
	<artifactId>springJPA</artifactId>
	<version>1</version>

	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.1.6.RELEASE</version>
	</parent>

	<properties>
		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
	</properties>



	<dependencies>


		<!-- https://mvnrepository.com/artifact/org.springframework.boot/spring-boot-starter-data-jpa -->
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-data-jpa</artifactId>
		</dependency>


		<!-- https://mvnrepository.com/artifact/com.h2database/h2 -->
		<dependency>
			<groupId>com.h2database</groupId>
			<artifactId>h2</artifactId>
		</dependency>


	</dependencies>

</project>

Total project structure looks like below.

Run App.java, you can able to see below messages in the console.

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v2.1.6.RELEASE)

Employee [id=1, firstName=Ram, lastName=Gurram, age=32, salary=100000.23, createdTime=2019-07-11 20:10:41.745, lastModifiedTime=2019-07-11 20:10:41.745, createdBy=Hari, modifiedBy=Hari]
Employee [id=2, firstName=Joel, lastName=Chelli, age=43, salary=60000.0, createdTime=2019-07-11 20:10:41.779, lastModifiedTime=2019-07-11 20:10:41.779, createdBy=Hari, modifiedBy=Hari]
Employee [id=3, firstName=Gopi, lastName=Battu, age=32, salary=1000000.0, createdTime=2019-07-11 20:10:41.782, lastModifiedTime=2019-07-11 20:10:41.782, createdBy=Hari, modifiedBy=Hari]
Employee [id=4, firstName=Bomma, lastName=Srikanth, age=39, salary=60000.0, createdTime=2019-07-11 20:10:41.783, lastModifiedTime=2019-07-11 20:10:41.783, createdBy=Hari, modifiedBy=Hari]
Employee [id=5, firstName=Surendra, lastName=Sami, age=32, salary=100000.23, createdTime=2019-07-11 20:10:41.785, lastModifiedTime=2019-07-11 20:10:41.785, createdBy=Hari, modifiedBy=Hari]
Employee [id=6, firstName=Bhadri, lastName=Venakata RamaRao, age=32, salary=100000.23, createdTime=2019-07-11 20:10:41.787, lastModifiedTime=2019-07-11 20:10:41.787, createdBy=Hari, modifiedBy=Hari]
Employee [id=7, firstName=Sushmithaa, lastName=Kulakarni, age=39, salary=100000.23, createdTime=2019-07-11 20:10:41.789, lastModifiedTime=2019-07-11 20:10:41.789, createdBy=Hari, modifiedBy=Hari]

You can download the complete application from this link.

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Tuesday 27 August 2019

Spring Data JPA: @CreatedBy and @LastModifiedBy

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