Pagination and Sorting Springboot

In this blog, we will explore how to implement pagination and sorting using Spring Boot, a popular Java-based framework for building robust and scalable web applications. We will also use the employee Rest spring boot application from our previous article below.

Introduction

Pagination is the process of dividing a large dataset into smaller, manageable chunks called "pages." This approach allows users to view and navigate through the data without overloading the application with all the information at once. A typical pagination system includes controls like "Previous," "Next," and page numbers to facilitate navigation.

To enable pagination in a Spring Boot application, you'll need to consider the following components:

1. Controller Layer: Begin by creating a RESTful API endpoint that will handle pagination requests. The endpoint should accept parameters like page number, page size, and sorting options.

2. Service Layer: Implement the business logic in the service layer to retrieve data from the database and apply pagination based on the provided parameters.

3. Repository Layer: Use Spring Data JPA's Pageable interface in your repository methods to handle pagination and sorting. This interface allows you to pass the pagination parameters to your queries easily.

4. Frontend Integration: On the frontend side, make sure to send the appropriate pagination parameters to the backend API, such as the desired page number, page size, and sorting criteria.

In this tutorial, we won't be focusing on the Frontend Integration but the backend part.

Repository

We extend the Jpa Repository because it includes all methods for paging and sorting. We could also extend PagingAndSortingRepository instead.

package com.alekinyua.restapiexceptions.repository;

import com.alekinyua.restapiexceptions.entity.Employee;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;

@Repository
public interface EmployeeRepository extends JpaRepository<Employee, Long> {
}

Employee Service

We will refactor the getAllEmployees method to return a page instead of a list.

public Page<Employee> getAllEmployees(int page, int size, String sortBy, String sortDirection){
    Sort sort = Sort.by(Sort.Direction.fromString(sortDirection), sortBy);
    Pageable pageable = PageRequest.of(page, size, sort);
    return employeeRepository.findAll(pageable);
}

We start by creating a Sort object based on the sortBy and sortDirection parameters. Then, you create a Pageable object using PageRequest.of and passing the page, size, and sort objects. Finally, you use this Pageable object to query the database using the repository.findAll(pageable) method, which should return a paginated and sorted Page of Employee entities.

Employee Controller

The controller method getAllEmployees maps the request parameters page, size, sortBy, and sortDirection to the corresponding method parameters and delegates the processing to the service method getAllEmployees.

@GetMapping("/employees")
public ResponseEntity<Page<Employee>> getAllEmployees(
        @RequestParam(defaultValue = "0") int page,
        @RequestParam(defaultValue = "10") int size,
        @RequestParam(defaultValue = "name") String sortBy,
        @RequestParam(defaultValue = "asc") String sortDirection
){
    return  ResponseEntity.ok(employeeService.getAllEmployees(page, size, sortBy, sortDirection));
}

Conclusion

In this blog, we explored the fundamental concepts of pagination and sorting and demonstrated how to implement them in a Spring Boot application. By using Spring Data JPA's Pageable and Sort interfaces, you can efficiently manage large datasets and provide a smoother user experience. Pagination and sorting are crucial for optimizing performance, reducing network loads, and delivering a seamless user interface, especially when dealing with substantial amounts of data in web applications.