What is the role of the Pageable interface in Spring Data MongoDB?

Table of Contents

• Introduction
• Role of the Pageable Interface
  • 1. What Is the **Pageable** Interface?
  • 2. How Does **Pageable** Work?
• Using the Pageable Interface in Spring Data MongoDB
  • 1. Creating a **Pageable** Object
    • Example: Basic Pagination
  • 2. Combining Pagination and Sorting
    • Example: Pagination with Sorting
• Practical Example: Paginated Query in Spring Boot with MongoDB
  • 1. User Entity
  • 2. User Repository
  • 3. User Service
  • 4. User Controller
  • Example Request
• Conclusion

Introduction

The Pageable interface in Spring Data MongoDB plays a crucial role in implementing pagination, a technique used to retrieve data in smaller, manageable chunks. Pagination is particularly useful when dealing with large datasets, as it minimizes memory usage and optimizes performance. This guide explains the purpose of the Pageable interface, its role in pagination, and how to use it effectively with practical examples.

Role of the Pageable Interface

1. What Is the **Pageable** Interface?

The Pageable interface is a part of Spring Data and provides a way to define pagination and sorting parameters. It abstracts the details of page size, current page, and sorting order, making it easier to query MongoDB collections.

Key features:

• Defines the page number (zero-based index).
• Specifies the page size (number of items per page).
• Allows for sorting by one or more fields in ascending or descending order.

2. How Does **Pageable** Work?

The Pageable object is typically used with repository methods in Spring Data MongoDB. By passing a Pageable instance to these methods, you can fetch a specific page of results from the MongoDB collection.

Using the Pageable Interface in Spring Data MongoDB

1. Creating a **Pageable** Object

You can create a Pageable object using the PageRequest.of() method. This method allows you to define the page number, size, and sorting criteria.

Example: Basic Pagination

In this example:

• PageRequest.of(page, size) creates a Pageable instance for the specified page and size.
• The findAll(pageable) method fetches the requested page of users.

2. Combining Pagination and Sorting

The Pageable interface also supports sorting. You can specify sorting criteria when creating a Pageable instance.

Example: Pagination with Sorting

Here:

• Sort.by(Sort.Order.asc("name")) specifies sorting by the name field in ascending order.
• PageRequest.of(page, size, sort) combines pagination and sorting.

Practical Example: Paginated Query in Spring Boot with MongoDB

1. User Entity

2. User Repository

3. User Service

4. User Controller

Example Request

You can test the endpoint with:

This will return the first page of users, with 5 users per page, sorted by name in ascending order.

Conclusion

The Pageable interface in Spring Data MongoDB simplifies pagination and sorting by abstracting complex query parameters. It is a powerful tool for efficiently handling large datasets, offering flexibility to define page size, page number, and sorting criteria. Combining the Pageable interface with repository methods in Spring Boot ensures that applications can deliver scalable and performance-optimized solutions for data retrieval.