Spring Data with JPA and @NamedQueries

If you use Spring Data and @NamedQuery annotations at your JPA entity you can easily use them in a more convenient way using the spring data repository.

On a previous blog we created a spring data project using spring boot and docker. We will use the pretty same project and enhance our repository’s functionality.

We will implement a named query that will fetch employees only if their Last Name has as many characters as the ones specified.

package com.gkatzioura.springdata.jpa.persistence.entity;

import javax.persistence.*;

/**
 * Created by gkatzioura on 6/2/16.
 */
@Entity
@Table(name = "employee", schema="spring_data_jpa_example")
@NamedQuery(name = "Employee.fetchByLastNameLength",
        query = "SELECT e FROM Employee e WHERE CHAR_LENGTH(e.lastname) =:length "
)
public class Employee {

    @Id
    @Column(name = "id")
    @GeneratedValue(strategy = GenerationType.SEQUENCE)
    private Long id;

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

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

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

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

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

    public Long getId() {
        return id;
    }

    public void setId(Long 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 String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public Integer getAge() {
        return age;
    }

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

    public Integer getSalary() {
        return salary;
    }

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

Pay extra attention to the query name and the convention we follow @{EntityName}.{queryName}.
Then we will add the method to our spring data repository.

package com.gkatzioura.springdata.jpa.persistence.repository;

import com.gkatzioura.springdata.jpa.persistence.entity.Employee;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.repository.query.Param;
import org.springframework.stereotype.Repository;

import java.util.List;

/**
 * Created by gkatzioura on 6/2/16.
 */
@Repository
public interface EmployeeRepository extends JpaRepository<Employee,Long>, EmployeeRepositoryCustom {

    List<Employee> fetchByLastNameLength(@Param("length") Long length);
}

And last but not least add some functionality to our controller.

package com.gkatzioura.springdata.jpa.controller;

import com.gkatzioura.springdata.jpa.persistence.entity.Employee;
import com.gkatzioura.springdata.jpa.persistence.repository.EmployeeRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

import java.util.List;

/**
 * Created by gkatzioura on 6/2/16.
 */
@RestController
public class TestController {

    @Autowired
    private EmployeeRepository employeeRepository;

    @RequestMapping("/employee")
    public List<Employee> getTest() {

        return employeeRepository.findAll();
    }

    @RequestMapping("/employee/filter")
    public List<Employee> getFiltered(String firstName,@RequestParam(defaultValue = "0") Double bonusAmount) {

        return employeeRepository.getFirstNamesLikeAndBonusBigger(firstName,bonusAmount);
    }

    @RequestMapping("/employee/lastnameLength")
    public List<Employee> fetchByLength(Long length) {
        return employeeRepository.fetchByLastNameLength(length);
    }

}

You can find the source code on github.

One thought on “Spring Data with JPA and @NamedQueries

  1. Nice example, keep it up! If you are using Eclipse IDE I believe the anqu method plugin could make your development of JPA named queries even faster.

    The plugin helps you to create the @NamedQuery annotations, has some auto-completion functionality for the query statement itself – and it generates the method signature for the repository from the query.

    Please note that the plugin has to be cofigured in the preferences concerning the modifiers of the generated method signature before you will get the result from the example.

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