Spring Data JPA CrudRepository findById()

In this article, we will see about Spring Data JPA CrudRepository findById() Example using Spring Boot and oracle.

The findById() method is used to retrieves an entity by its id and it is available in CrudRepository interface. The CrudRepository extends Repository interface. In Spring Data JPA Repository is top-level interface in hierarchy. Here we are going to see findById() method of CrudRepository. The findById() method has been defined as below.

Optional<T> findById(ID id);

Note – Optional is a class introduced in java 8.

Using findById() method we can get a single record(entity) on basis of id.

Internally findById() method use EntityManger’s find() method(as below).

	public Optional<T> findById(ID id) {

		// some more code

		if (metadata == null) {
			return Optional.ofNullable(em.find(domainType, id));
		}

                //some more code

		return Optional.ofNullable(type == null ? em.find(domainType, id, hints) : em.find(domainType, id, type, hints));
	}

Let’s see in below code how to use the Spring Data JPA CrudRepository findById() method for get operation.

package com.netsurfingzone.impl;

import java.util.Optional;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import com.netsurfingzone.entity.Student;
import com.netsurfingzone.repository.StudentRepository;
import com.netsurfingzone.service.StudentService;

@Service("studentServiceImpl")
public class StudentServiceImpl implements StudentService {

	@Autowired
	private StudentRepository studentRepository;

	@Transactional
	public Student saveStudent(Student student) {
		Student response =  studentRepository.save(student);
		return response;
	}

	@Transactional(readOnly = true)
	public Student getStudent(int id ) {
		Optional<Student> studentResponse =  studentRepository.findById(id);
		Student student = studentResponse.get();
		return student;
	}
	
}

Let’s see an example of Spring Data JPA CrudRepository findById() Example where we will use save() method for creating the entity and findById() to get a single record.

Open eclipse and create maven project, Don’t forget to check ‘Create a simple project (skip)’ click on next.  Fill all details(GroupId – springdatafindbyid, ArtifactId – springdatafindbyid and name – springdatafindbyid) and click on finish. Keep packaging as the jar.

Modify 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>springdatafindbyid</groupId>
	<artifactId>springdatafindbyid</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<name>springdatafindbyid</name>
	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.0.2.RELEASE</version>
	</parent>
	<dependencies>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-web</artifactId>

		</dependency>

		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-data-jpa</artifactId>
		</dependency>

		<dependency>
			<groupId>com.oracle</groupId>
			<artifactId>ojdbc6</artifactId>
			<version>11.2.0.3</version>
		</dependency>

	</dependencies>
	<build>
		<finalName>${project.artifactId}</finalName>
		<plugins>

			<plugin>
				<artifactId>maven-compiler-plugin</artifactId>
				<version>3.1</version>
				<configuration>
					<fork>true</fork>
					<executable>C:\Program Files\Java\jdk1.8.0_131\bin\javac.exe</executable>
				</configuration>
			</plugin>


		</plugins>
	</build>
</project>

Note – In pom.xml we have defined javac.exe path in configuration tag. You need to change accordingly i.e where you have installed JDK.


If you see any error for oracle dependency then follow these steps.

Directory structure –

Spring Data JPA CrudRepository finById()

Student.java

package com.netsurfingzone.entity;

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

@Entity
public class Student {

	@Id
	@GeneratedValue(strategy = GenerationType.AUTO)
	private int id;

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

	@Column(name = "roll_number")
	private String rollNumber;

	@Column(name = "university")
	String university;

	public int getId() {
		return id;
	}

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

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public String getRollNumber() {
		return rollNumber;
	}

	public void setRollNumber(String rollNumber) {
		this.rollNumber = rollNumber;
	}

	public String getUniversity() {
		return university;
	}

	public void setUniversity(String university) {
		this.university = university;
	}

}

StudentController.java

package com.netsurfingzone.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.RestController;

import com.netsurfingzone.entity.Student;
import com.netsurfingzone.service.StudentService;

@RestController
@RequestMapping(value = "/student")
public class StudentController {

	@Autowired
	private StudentService studentService;

	@RequestMapping(value = "/save", method = RequestMethod.POST)
	@ResponseBody
	public Student save(@RequestBody Student student) {
		Student studentResponse = (Student) studentService.saveStudent(student);
		return studentResponse;
	}

	@RequestMapping(value = "/{id}", method = RequestMethod.GET)
	@ResponseBody
	public Student getStudent(@PathVariable int id) {
		Student studentResponse = (Student) studentService.getStudent(id);
		return studentResponse;
	}

}

StudentRepository.java – interface

package com.netsurfingzone.repository;

import java.io.Serializable;

import org.springframework.data.repository.CrudRepository;
import org.springframework.stereotype.Repository;

import com.netsurfingzone.entity.Student;

@Repository
public interface StudentRepository extends CrudRepository<Student, Serializable> {

}

StudentService.java – interface


package com.netsurfingzone.service;

import org.springframework.stereotype.Component;

import com.netsurfingzone.entity.Student;

@Component
public interface StudentService {
	public Student saveStudent(Student student);

	public Student getStudent(int id);

}

StudentServiceImpl.java

package com.netsurfingzone.impl;

import java.util.Optional;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import com.netsurfingzone.entity.Student;
import com.netsurfingzone.repository.StudentRepository;
import com.netsurfingzone.service.StudentService;

@Service("studentServiceImpl")
public class StudentServiceImpl implements StudentService {

	@Autowired
	private StudentRepository studentRepository;

	@Transactional
	public Student saveStudent(Student student) {
		Student response =  studentRepository.save(student);
		return response;
	}

	@Transactional(readOnly = true)
	public Student getStudent(int id ) {
		Optional<Student> studentResponse =  studentRepository.findById(id);
		Student student = studentResponse.get();
		return student;
	}
	
}

SpringMain.java

package com.netsurfingzone.main;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.domain.EntityScan;
import org.springframework.context.annotation.ComponentScan;

@SpringBootApplication
@ComponentScan(basePackages = "com.*")
@EntityScan("com.netsurfingzone.entity")
public class SpringMain {
	public static void main(String[] args) {

		SpringApplication.run(SpringMain.class, args);
	}

}

JpaConfig.java

package com.netsurfingzone.config;

import org.springframework.context.annotation.Configuration;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;

@Configuration
@EnableJpaRepositories(basePackages = "com.netsurfingzone.repository")
public class JpaConfig {

}

application.properties

# Connection url for the database
spring.datasource.url=jdbc:oracle:thin:@localhost:1521:XE
spring.datasource.username=SYSTEM
spring.datasource.password=oracle2
spring.datasource.driver-class-name=oracle.jdbc.driver.OracleDriver
# Show or not log for each sql query
spring.jpa.show-sql = true
 
 
spring.jpa.hibernate.ddl-auto =create
spring.jpa.properties.hibernate.dialect = org.hibernate.dialect.Oracle10gDialect
 
server.port = 9091

Let’s run the SpringMain class(run as java application).

Perform save operation first using below REST API.


http://localhost:9091/student/save

Request Data –

 {

        "name": "Hiteshdo",
        "rollNumber": "0126CS01",
        "university": "rgtu"
}

Response data –

{
    "id": 1,
    "name": "Hiteshdo",
    "rollNumber": "0126CS01",
    "university": "rgtu"
}

Get operation.

API -http://localhost:9091/student/{id}

http://localhost:9091/student/1

Spring Data JPA CrudRepository finById()

See brief about Spring Data JPA Repository hierarchy as below.

You may like.

Other Spring Data JPA and Hibernate tutorials.

Spring Data JPA findById() docs.