"<p>Efficiently managing data is key to a seamless web application experience, especially when dealing with large datasets. In this tutorial, we'll explore how to implement pagination using Node.js and Sequelize, a powerful ORM for Node.js applications.</p> <h3>Environment Setup</h3> <p>Ensure you have Node.js and Sequelize installed. If not, you can install them via npm:</p> <pre class="language-javascript"><code>npm install sequelize sequelize-cli mysql2</code></pre> <p>Configure your Sequelize connection settings in <code>config/config.json</code> to connect to your database as we did it in this tutorial : <a href="tutorials/node-js-database-setup">https://devbrains.tn/tutorials/node-js-database-setup</a></p> <h3>Pagination Logic</h3> <p>Let's start by creating a function to fetch posts with pagination. Here's the code:</p> <pre class="language-javascript"><code>import { Post } from '../models'; // Assuming a Post model exists export const getAllPosts = async (req, res) => { try { let { page = 1, itemsPerPage = 5 } = req.query; const params = {}; page = parseInt(page); itemsPerPage = parseInt(itemsPerPage); if ((page && page > 0) && (itemsPerPage && itemsPerPage >= 5 && itemsPerPage <= 50)) { params.limit = itemsPerPage; params.offset = (page - 1) * itemsPerPage; } const { count, rows } = await Post.findAndCountAll(params); return res.status(200).json({ pagination: { count }, data: rows }); } catch (error) { return res.status(500).json({ message: "Internal Server Error" }); } } </code></pre> <h3>How It Works</h3> <ol> <li> <p><strong>Importing Modules and Models</strong>: Import necessary modules like <code>sequelize</code> and relevant models, such as the <code>Post</code> model.</p> </li> <li> <p><strong>Pagination Parameters Handling</strong>: The function handles <code>page</code> and <code>itemsPerPage</code> query parameters, setting defaults if not provided.</p> </li> <li> <p><strong>Parameter Parsing</strong>: Ensures parameters are integers for accurate calculations.</p> </li> <li> <p><strong>Pagination Logic</strong>: Validates provided parameters and computes <code>limit</code> and <code>offset</code> for Sequelize's <code>findAndCountAll</code> method.</p> </li> <li> <p><strong>Data Retrieval</strong>: Utilizes Sequelize's <code>findAndCountAll</code> to fetch paginated data and total count.</p> </li> <li> <p><strong>Response Formatting</strong>: Returns a JSON response with pagination metadata and paginated data.</p> </li> </ol> <h3>Testing Pagination</h3> <p>To test the setup, send requests to your Node.js server with varying <code>page</code> and <code>itemsPerPage</code> values:</p> <pre class="language-markup"><code>GET /api/posts?page=1&itemsPerPage=10 GET /api/posts?page=2&itemsPerPage=5</code></pre> <p> </p>"