In this tutorial, we will see Spring Data JPA Projection Example using Spring Boot and oracle. We will see how to implement Projection using Spring Data JPA.
Consider we have an entity called Student.java as below.
package com.javatute.entity;
@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;
}
and we have some record in the database as below.
We want to fetch any single column. For example, we want all student name as below.
Let’s see how to define Projection for the above requirement.
Define Interface with some method.
package com.javatute.repository;
public interface StudentName {
String getName();
}
Define Repository as below.
@Repository
public interface StudentRepository extends JpaRepository<Student, Serializable> {
List<StudentName> findAllBy();
}
Generated query.
Hibernate:
select
student0_.name as col_0_0_
from
student student0_
Running below example we should able to fetch name column details as below.
Spring Data JPA Projection Example using Spring Boot and Oracle.
Open eclipse and create maven project, Don’t forget to check ‘Create a simple project (skip)’ click on next. Fill all details(GroupId – springdataprojection, ArtifactId – springdataprojection and name – springdataprojection) 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>springdataprojection</groupId>
<artifactId>springdataprojection</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>springdataprojection</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.
Let’s see the entity for Spring Data JPA Projection Example using Spring Boot.
Student.java
package com.javatute.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.javatute.controller;
import java.util.ArrayList;
import java.util.List;
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.javatute.entity.Student;
import com.javatute.repository.StudentName;
import com.javatute.service.StudentService;
@RestController
@RequestMapping(value = "/student")
public class StudentController {
@Autowired
private StudentService studentService;
@RequestMapping(value = "/saveall", method = RequestMethod.POST)
@ResponseBody
public List<Student> saveAllStudents(@RequestBody List<Student> studentList) {
List<Student> studentResponse = (List<Student>) studentService.saveAllStudent(studentList);
return studentResponse;
}
@RequestMapping(value = "/findallname", method = RequestMethod.GET)
@ResponseBody
public List<String> findAllBy() {
List<StudentName> studentResponse = (List<StudentName>) studentService.findAllBy();
List<String> nameList = new ArrayList<String>();
for(StudentName studentName : studentResponse) {
nameList.add(studentName.getName());
}
return nameList;
}
}
Note – See more details about @Controller and RestController here.
StudentRepository.java – interface
package com.javatute.repository;
import java.io.Serializable;
import java.util.List;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;
import com.javatute.entity.Student;
@Repository
public interface StudentRepository extends JpaRepository<Student, Serializable> {
List<StudentName> findAllBy();
}
Define Interface StudentName with method getName..
package com.javatute.repository;
public interface StudentName {
String getName();
}
StudentService.java – interface
package com.javatute.service;
import java.util.List;
import org.springframework.stereotype.Component;
import com.javatute.entity.Student;
import com.javatute.repository.StudentName;
@Component
public interface StudentService {
public List<Student> saveAllStudent(List<Student> studentList);
List<StudentName> findAllBy();
}
Note – See here more about @Component, @Controller, @Service and @Repository annotations here.
StudentServiceImpl.java
package com.javatute.impl;
import java.util.List;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import com.javatute.entity.Student;
import com.javatute.repository.StudentName;
import com.javatute.repository.StudentRepository;
import com.javatute.service.StudentService;
@Service("studentServiceImpl")
public class StudentServiceImpl implements StudentService {
@Autowired
private StudentRepository studentRepository;
@Transactional
public List<Student> saveAllStudent(List<Student> studentList) {
List<Student> response = (List<Student>) studentRepository.saveAll(studentList);
return response;
}
@Transactional
public List<StudentName> findAllBy() {
List<StudentName> response = (List<StudentName>) studentRepository.findAllBy();
return response;
}
}
SpringMain.java
package com.javatute.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.javatute.entity")
public class SpringMain {
public static void main(String[] args) {
SpringApplication.run(SpringMain.class, args);
}
}
Note – See more details about @ComponentScan here.
JpaConfig.java
package com.javatute.config;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;
@Configuration
@EnableJpaRepositories(basePackages = "com.javatute.repository")
public class JpaConfig {
}
Note – See more details about @Configuration annotations here.
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.properties.hibernate.format_sql=true spring.jpa.hibernate.ddl-auto =create spring.jpa.properties.hibernate.dialect = org.hibernate.dialect.Oracle10gDialect server.port = 9091 #show sql values logging.level.org.hibernate.type.descriptor.sql=trace #hibernate.show_sql = true #spring.jpa.hibernate.logging.level.sql =FINE #show sql statement #logging.level.org.hibernate.SQL=debug
Let’s run the SpringMain class(run as java application).
Perform saveall operation first using below REST API.
http://localhost:9091/student/saveall
[
{
"name": "john",
"rollNumber": "120",
"university":"rgtu"
},
{
"name": "mark",
"rollNumber": "121",
"university":"rgtu"
},
{
"name": "aric",
"rollNumber": "123",
"university":"rgtu"
},
{
"name": "hira",
"rollNumber": "124",
"university":"rgtu"
}
]
Let’s see response data for Spring Data JPA Projection Example.
Response Data.
[
{
"id": 1,
"name": "john",
"rollNumber": "120",
"university": "rgtu"
},
{
"id": 2,
"name": "mark",
"rollNumber": "121",
"university": "rgtu"
},
{
"id": 3,
"name": "aric",
"rollNumber": "123",
"university": "rgtu"
},
{
"id": 4,
"name": "hira",
"rollNumber": "124",
"university": "rgtu"
}
]
http://localhost:9091/student/findallname
That’s all about Spring Data JPA Projection Example Using Spring Boot and oracle.
You may like.
- Spring Data JPA greater than Example
- Spring Data JPA less than Example
- Spring Data JPA IsNull Example Using Spring Boot
- Spring Data findById() Vs getOne()
- Spring Data JPA CrudRepository findById()
- Spring Data JPA JpaRepository getOne()
- Spring Data CrudRepository saveAll() and findAll().
- Spring Data CrudRepository existsById()
- Spring Data JPA delete() vs deleteInBatch()
- Spring Data JPA deleteAll() Vs deleteAllInBatch()
- Spring Data JPA JpaRepository deleteAllInBatch()
- Spring Data JPA deleteInBatch() Example
- Spring Data JPA JpaRepository saveAndFlush() Example
- Spring Data JPA CrudRepository count() Example
- Spring Data JPA CrudRepository delete() and deleteAll()
- Spring Data JPA CrudRepository deleteById() Example
- CrudRepository findAllById() Example Using Spring Boot
- Spring Data CrudRepository save() Method.
- Sorting in Spring Data JPA using Spring Boot.
- Spring Data JPA example using spring boot.
- Spring Data JPA and its benefit.
Other Spring Data JPA and Hibernate tutorials.
- @Version Annotation Example In Hibernate.
- Hibernate Validator Constraints Example Using Spring Boot.
- @Temporal Annotation Example In Hibernate/Jpa Using Spring Boot.
- Hibernate Table Per Concrete Class Spring Boot.
- Hibernate Table Per Subclass Inheritance Spring Boot.
- Hibernate Single Table Inheritance using Spring Boot.
- One To One Mapping Annotation Example in Hibernate/JPA using Spring Boot and Oracle.
- One To One Bidirectional Mapping Example In Hibernate/JPA Using Spring Boot and Oracle.
- One To Many Mapping Annotation Example In Hibernate/JPA Using Spring Boot And Oracle.
- Many To One Unidirectional Mapping In Hibernate/JPA Annotation Example Using Spring Boot and Oracle.
- One To Many Bidirectional Mapping In Hibernate/JPA Annotation Example Using Spring Boot and Oracle.
- Many To Many Mapping Annotation Example In Hibernate/JPA Using Spring Boot And
Spring Data JPA Docs.
