Pagination API with Sping Boot
Published in Pagination
Prasomsak Khunmuen

Create a pagination API with Spring Boot

Splitting larger content into distinct pages is known as pagination. This method significantly enhances the user experience and speeds up the loading of web pages. This example will demonstrate how to create a pagination API using Spring-Boot and use MySQL as a database.

Prerequisites

  • JAVA 17
  • Maven
  • MySQL

Setup project

Create a testing database named "example" and run the database.sql file to import the table and data.

Project structure

├─ pom.xml
└─ src
   └─ main
      ├─ java
      │  └─ com
      │     └─ stackpuz
      │        └─ example
      │           ├─ App.java
      │           ├─ controller
      │           │  └─ ProductController.java
      │           ├─ entity
      │           │  └─ Product.java
      │           └─ repository
      │              └─ ProductRepository.java
      └─ resources
         ├─ application.properties
         └─ static
            └─ index.html

Project files

pom.xml

This file contains the configuration and dependencies of the Maven project.

<?xml version="1.0" encoding="UTF-8"?>
<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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<groupId>com.stackpuz</groupId>
	<artifactId>example-pagination</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<name>example-pagination</name>
	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>3.0.10</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>org.springframework.boot</groupId>
	        <artifactId>spring-boot-devtools</artifactId>
	    </dependency>
		<dependency>
			<groupId>mysql</groupId>
			<artifactId>mysql-connector-java</artifactId>
			<version>8.0.30</version>
		</dependency>
		<dependency>
			<groupId>org.projectlombok</groupId>
			<artifactId>lombok</artifactId>
		</dependency>
	   </dependencies>
</project>

application.properties

This file contains the database configuration.

spring.datasource.url = jdbc:mysql://localhost/example
spring.datasource.username = root
spring.datasource.password = 
spring.jpa.properties.hibernate.dialect = org.hibernate.dialect.MySQLDialect

App.java

This file is the main entry point for the Spring Boot application.

package com.stackpuz.example;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class App {
	public static void main(String[] args) {
		SpringApplication.run(App.class, args);
	}
}

ProductRepository.java

This file defines the product repository by utilizing the PagingAndSortingRepository class, which has the pagination feature, so we can use it to implement the pagination with less effort.

package com.stackpuz.example.repository;

import com.stackpuz.example.entity.Product;
import org.springframework.data.repository.PagingAndSortingRepository;

public interface ProductRepository extends PagingAndSortingRepository<Product, Integer> {
    
}

Product.java

This file defines the product entity that maps to our database table named "Product".

package com.stackpuz.example.entity;

import jakarta.persistence.Entity;
import jakarta.persistence.GeneratedValue;
import jakarta.persistence.*;
import lombok.Getter;
import lombok.NoArgsConstructor;
import lombok.Setter;

import java.math.BigDecimal;

@Entity
@Getter
@Setter
@NoArgsConstructor
public class Product {

    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    private int id;
    private String name;
    private BigDecimal price;
}
  • We use the lombok library features to reduce the amount of code written for our entity by using @Getter @Setter @NoArgsConstructor

ProductController.java

This file is used to handle incoming requests and produce the paginated data for the client.

package com.stackpuz.example.controller;

import java.util.Optional;
import com.stackpuz.example.entity.Product;
import com.stackpuz.example.repository.ProductRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.domain.*;
import org.springframework.data.domain.Sort.Direction;
import org.springframework.web.bind.annotation.*;

import java.util.List;

@RestController
public class ProductController {

    @Autowired
    private ProductRepository repository;

    @GetMapping("/api/products")
    public List<Product> getProducts(@RequestParam("page") Optional<Integer> pageParam, @RequestParam("size") Optional<Integer> sizeParam, @RequestParam("order") Optional<String> orderParam, @RequestParam("direction") Optional<String> directionParam) {
        int page = pageParam.orElse(1) - 1;
        int size = sizeParam.orElse(10);
        String order = orderParam.orElse("id");
        String direction = directionParam.orElse("asc");
        return repository.findAll(PageRequest.of(page, size, Sort.by(Direction.fromString(direction), order))).getContent();
    }
}
  • We use @RequestParam to map each query string to the URL.
  • Because Spring Boot page index is starts at zero, so we use pageParam.orElse(1) - 1 for this purpose.
  • repository.findAll() receives the Pageable object as the parameter. We create this Pageable object by using the PageRequest.of() method.
  • repository.findAll() will return Page<T> object that contains all information about paginated data, but in this case we just want to return the product data, so we use getContent() here.

Index.html

Instead of entering the URL manually to test our API, we used this file to create links for easier testing.

<!DOCTYPE html>
<head>
</head>
<body>
    <ul>
        <li><a target="_blank" href="/api/products">Default</a></li>
        <li><a target="_blank" href="/api/products?page=2">Page 2</a></li>
        <li><a target="_blank" href="/api/products?page=2&size=25">Page 2 and Size 25</a></li>
        <li><a target="_blank" href="/api/products?page=2&size=25&order=name">Page 2 and Size 25 and Order by name</a></li>
        <li><a target="_blank" href="/api/products?page=2&size=25&order=name&direction=desc">Page 2 and Size 25 and Order by name descending</a></li>
    </ul>
</body>
</html>

Run project

mvn spring-boot:run

Open the web browser and goto http://localhost:8080

You will find this test page.

test page

Testing

Testing without any parameters

Click the "Default" link, and it will open the URL http://localhost:8080/api/products

default test

The API will return paginated data with default parameters (page = 1 and size = 10).

Page index testing

Click the "Page 2" link, and it will open the URL http://localhost:8080/api/products?page=2

page index test

The API will return paginated data on the second page, starting with product id 11

Page size testing

Click the "Page 2 and Size 25" link, and it will open the URL http://localhost:8080/api/products?page=2&size=25

page size test

The API will return paginated data on the second page by starting with product id 26 because the page size is 25.

Order testing

Click the "Page 2 and Size 25 and Order by name" link, and it will open the URL http://localhost:8080/api/products?page=2&size=25&order=name

order test

The API will return paginated data on the second page, but the product order is based on the product name.

Descending order testing

Click the "Page 2 and Size 25 and Order by name descending" link, and it will open the URL http://localhost:8080/api/products?page=2&size=25&order=name&direction=desc

descending order test

The API will return paginated data on the second page, but the product order is based on the product name in descending order.

Conclusion

In this article, you have learned how to utilize the PagingAndSortingRepository class to implement the pagination API for our web application with less effort. This will enhance the user experience and speed up your Spring Boot application. If you like this article please share it with your friends.

Source code: https://github.com/stackpuz/Example-Pagination-Spring-Boot-3

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