How to implement pagination with MongoDB in a Node.js application



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Implementing pagination in a Node.js application with MongoDB involves using the skip() and limit() methods provided by MongoDB queries. Additionally, you may need to keep track of the current page and the number of items per page. Here's a basic example using the mongoose library, which is a popular MongoDB ODM (Object-Document Mapper) for Node.js:

  1. Install the required npm packages:
bash
npm install mongoose
  1. Set up your MongoDB connection and create a mongoose model for your collection. Here's an example:
javascript
// app.js

const mongoose = require('mongoose');

// Connect to MongoDB
mongoose.connect('mongodb://localhost:27017/your-database-name', {
  useNewUrlParser: true,
  useUnifiedTopology: true,
});

// Create a mongoose model
const YourModel = mongoose.model('YourModel', {
  // Define your schema here
  // ...
});
  1. Implement pagination in your route or controller:
javascript
// app.js

const express = require('express');
const app = express();
const port = 3000;

const YourModel = require('./yourModel'); // Make sure to provide the correct path

app.get('/your-route', async (req, res) => {
  const page = parseInt(req.query.page) || 1; // Current page, default is 1
  const pageSize = parseInt(req.query.pageSize) || 10; // Number of items per page, default is 10

  try {
    // Calculate the skip value based on the page and pageSize
    const skip = (page - 1) * pageSize;

    // Fetch data with pagination using the skip and limit methods
    const data = await YourModel.find()
      .skip(skip)
      .limit(pageSize);

    res.json({
      data,
      page,
      pageSize,
    });
  } catch (error) {
    console.error(error);
    res.status(500).json({ error: 'Internal Server Error' });
  }
});

app.listen(port, () => {
  console.log(`Server is running on http://localhost:${port}`);
});

In this example, the /your-route endpoint accepts query parameters page and pageSize to implement pagination. The skip() method is used to skip a certain number of documents, and the limit() method is used to limit the number of documents returned.

You can make a request to /your-route?page=1&pageSize=10 to get the first page with 10 items, /your-route?page=2&pageSize=10 for the second page, and so on.

Remember to customize the code according to your schema and application requirements. Additionally, handle errors appropriately in a production environment.

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