Spring Data CrudRepository existsById()

In this tutorial, we will see about Spring Data CrudRepository existsById() Method using Spring Boot and Oracle.

Spring Data CrudRepository existsById()

CrudRepository interface extends Repository interface. In Spring Data JPA Repository is top-level interface in hierarchy. Here we are going to see existsById() method of CrudRepository. The existsById() method has been defined as below.

boolean existsById(ID id);

The CrudRepository existsById() method is used to check whether an entity exists in the database or not. It will return true if entity for given id exists in the database else false. Internally existsById() uses CrudRepository findById() method only.

	public boolean existsById(ID id) {

		if (entityInformation.getIdAttribute() == null) {
			return findById(id).isPresent();
		}
                // some more code

	}

Note – existsById(ID id)  returns boolean where as findById(ID id) returns Optional(Object). We can get object from Optional class using get() method(see more details here).


Spring Data CrudRepository existsById() Sample.

Let’s see in below code how we are going to use the CrudRepository existsById() method.

@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 boolean isStudentExists(int id) {
		if (studentRepository.existsById(id)) {
			return true;
		}
		return false;
	}

}

 

Let’s see an example of Spring Data JPA CrudRepository existsById() Method.

Open eclipse and create maven project, Don’t forget to check ‘Create a simple project (skip)’ click on next.  Fill all details(GroupId – springdataexistsById, ArtifactId – springdataexistsById and name – springdataexistsById) 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>springdataexistsById</groupId>
	<artifactId>springdataexistsById</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<name>springdataexistsById</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 CrudRepository save() Method

 

 

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 java.util.Optional;

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

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

	@Autowired
	private StudentService studentService;

	@Autowired
	private StudentRepository studentRepository;

	@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) {

		if (studentService.isStudentExists(id)) {
			Optional<Student> optional = studentRepository.findById(id);
			Student studentResponse = optional.get();
			return studentResponse;
		} else {
			throw new RuntimeException("Student doesn't exists for id: - " + id);
		}

	}

}

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 boolean isStudentExists(int id);

}

 

StudentServiceImpl.java

package com.netsurfingzone.impl;

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 boolean isStudentExists(int id) {
		if (studentRepository.existsById(id)) {
			return true;
		}
		return false;
	}

}

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.

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 CrudRepository existsById()

Suppose you try to fetch Student entity on basis of id 2, you will get below response.

 

See brief about Spring Data JPA Repository hierarchy as below.

 

That’s all about Spring Data CrudRepository existsById().

You may like.

Other Spring Data JPA and Hibernate tutorials.

Spring Data JPA existsById() docs.

We have seen Spring Data CrudRepository existsById() method.ummu

Summary – Spring Data CrudRepository existsById() Method used to check whether an entity exists in the database or not. It will return true if entity for given id exists in the database else false.