How do you create a paginated REST API with Spring Data?

Table of Contents

• Introduction
  • Steps to Create a Paginated REST API with Spring Data
    • 1. Set Up Spring Boot Project with Spring Data JPA
    • 2. Create a JPA Entity
    • 3. Create a Repository Interface with Paging Support
    • 4. Create a Service Layer to Handle Pagination
    • 5. Create a REST Controller to Handle HTTP Requests
    • 6. Test the API
• Conclusion

Introduction

When building REST APIs with Spring Boot, it’s common to handle large datasets by implementing pagination. Pagination allows clients to request data in chunks, making it easier to manage and load. Spring Data JPA makes it easy to implement pagination in your REST APIs with just a few lines of code. In this guide, we will walk you through how to create a paginated REST API using Spring Data JPA.

Steps to Create a Paginated REST API with Spring Data

1. Set Up Spring Boot Project with Spring Data JPA

First, ensure that you have a Spring Boot application with Spring Data JPA enabled. Add the necessary dependencies to your pom.xml if they are not already included.

Add Dependencies in **pom.xml**

Configure **application.properties**

2. Create a JPA Entity

Create an entity that will be mapped to a table in the database. For this example, let’s create a Product entity.

Example: **Product** Entity

3. Create a Repository Interface with Paging Support

To enable pagination in Spring Data JPA, your repository interface should extend JpaRepository or PagingAndSortingRepository. These interfaces provide built-in methods like findAll(Pageable pageable) that allow you to fetch paginated data.

Example: **ProductRepository** Interface

Here, the findByNameContaining method fetches products based on the name, and the results are returned as a Page object, which includes pagination details such as the total number of pages, the current page, and the data itself.

4. Create a Service Layer to Handle Pagination

In the service layer, use the repository’s methods to fetch data with pagination. You can also customize the Pageable object to specify the page number, size, and sorting criteria.

Example: **ProductService** Class

In this service:

• getProducts() fetches all products with pagination and sorting.
• getProductsByName() fetches products filtered by name, with pagination and sorting.

5. Create a REST Controller to Handle HTTP Requests

Now, create a REST controller that will expose the paginated data through HTTP endpoints. You can pass pagination parameters such as page, size, and sorting criteria through query parameters.

Example: **ProductController** Class

In this controller:

• The /products endpoint accepts query parameters for pagination (page, size) and sorting (sortBy, ascending).
• The /products/search endpoint allows filtering by product name while still supporting pagination and sorting.

For example:

• GET /products?page=0&size=5&sortBy=price&ascending=false
• GET /products/search?name=phone&page=0&size=5&sortBy=name&ascending=true

6. Test the API

You can now test the paginated REST API using tools like Postman, cURL, or by simply accessing the endpoints in your browser.

For example:

• GET http://localhost:8080/products?page=0&size=10&sortBy=price&ascending=true will fetch the first 10 products, sorted by price in ascending order.
• GET http://localhost:8080/products/search?name=phone&page=0&size=5&sortBy=name&ascending=false will fetch products containing "phone" in their name, paginated and sorted by name in descending order.

Conclusion

Creating a paginated REST API in Spring Boot using Spring Data JPA is straightforward and efficient. By leveraging Pageable and Page from Spring Data, you can implement pagination and sorting with minimal code. This approach not only improves the performance of your API but also provides a better user experience when dealing with large datasets. With the REST endpoints exposed, clients can easily query for paginated and sorted data, enabling them to handle large volumes of information effectively.