Tuesday, 27 August 2019

Spring Data JPA: Read only repository


In this post, I am going to explain how to create read only repository (where you can’t perform update, delete operations).

Step 1: Create 'ReadOnlyRepository' interface that extends Repository interface and annotate this interface with @NoRepositoryBean annotation.
@NoRepositoryBean
public interface ReadOnlyRepository<T, ID> extends Repository<T, ID> {

}


Step 2: Add read methods to ReadOnlyRepository interface.
@NoRepositoryBean
public interface ReadOnlyRepository<T, ID> extends Repository<T, ID> {

    <S extends T> S save(S entity);

    <S extends T> Iterable<S> saveAll(Iterable<S> entities);

    Optional<T> findById(ID id);

    boolean existsById(ID id);

    Iterable<T> findAll();

    Iterable<T> findAllById(Iterable<ID> ids);

    long count();

}


Step 3: Now extend 'ReadOnlyRepository' to work with these read methods.
public interface EmployeeRepository extends ReadOnlyRepository<Employee, Integer> {

}

That’s it you are done.

Find the below working application.

Employee.java
package com.sample.app.model;

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

@Entity
@Table(name = "my_employee")
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;

    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 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;
        }
    }

    @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("]");
        return builder.toString();
    }



}


ReadOnlyRepository.java
package com.sample.app.repository;

import java.util.Optional;

import org.springframework.data.repository.NoRepositoryBean;
import org.springframework.data.repository.Repository;

@NoRepositoryBean
public interface ReadOnlyRepository<T, ID> extends Repository<T, ID> {

    <S extends T> S save(S entity);

    <S extends T> Iterable<S> saveAll(Iterable<S> entities);

    Optional<T> findById(ID id);

    boolean existsById(ID id);

    Iterable<T> findAll();

    Iterable<T> findAllById(Iterable<ID> ids);

    long count();

}


EmployeeRepository.java
package com.sample.app.repository;

import com.sample.app.model.Employee;

public interface EmployeeRepository extends ReadOnlyRepository<Employee, Integer> {

}


App.java
package com.sample.app;

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.jpa.repository.config.EnableJpaAuditing;

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);

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

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

        };
    }

}

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


Total project structure looks like below.


Run App.java, you can see below messages in console.
  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v2.1.6.RELEASE)

Employee [id=1, firstName=Ram, lastName=Gurram, age=32, salary=100000.23]
Employee [id=2, firstName=Joel, lastName=Chelli, age=43, salary=60000.0]
Employee [id=3, firstName=Gopi, lastName=Battu, age=32, salary=1000000.0]
Employee [id=4, firstName=Bomma, lastName=Srikanth, age=39, salary=60000.0]
Employee [id=5, firstName=Surendra, lastName=Sami, age=32, salary=100000.23]
Employee [id=6, firstName=Bhadri, lastName=Venakata RamaRao, age=32, salary=100000.23]
Employee [id=7, firstName=Sushmithaa, lastName=Kulakarni, age=39, salary=100000.23]

You can download the complete working application from this link.


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