How to do Pagination in Node.js using Sorting Ids ?
Implementing pagination in a Node.js application involves fetching and displaying data in chunks or pages, typically from a database. One common approach to pagination is using sorting IDs, where each record in the dataset is assigned a unique identifier (ID) that determines its position in the sorted sequence. This method allows you to efficiently retrieve data based on these IDs to implement pagination. Let’s dive into how you can achieve pagination using sorting IDs in a Node.js application.
Approach
Sorting in the NodeJS helps to sort the results in ascending or descending order. We use the sort() method in which we pass one parameter that results in ascending or descending order. Use the value -1 in the sort object to sort descending and 1 to sort the object in the ascending order.
Below are two implementations of pagination
Table of Content
- Sorting in ascending order using IDs
- Sorting in descending order using IDs
Steps to Setup the Project
Step 1: Create a nodeJS folder by using this command
mkdir mypp
Step 2: Navigate to the project directory
cd myapp
Step 3: Initialize the NodeJS project
npm init
Step 4: Install the necessary packages/libraries in your project using the following commands.
npm install mongoose express bcryptjs body-parser
Project Structure:
The updated dependencies in package.json file will look like:
"dependencies": {
"bcryptjs": "^2.4.3",
"body-parser": "^1.20.2",
"express": "^4.19.2",
"mongoose": "^8.4.1"
}
MongoDB Database:
Following is the sample data stored in your database for this example.
Sorting in ascending order using IDs
// user.js
let mongoose = require("mongoose");
let userSchema = new mongoose.Schema({
username:String,
password:String
});
module.exports = mongoose.model("User",userSchema);
// app.js
const express = require('express'),
Mongoose = require('mongoose'),
Bcrypt = require('bcryptjs'),
bodyParser = require('body-parser'),
jsonParser = bodyParser.json(),
User = require('./user')
const app = express();
const db = `mongodb+srv://pallavi:pallavi123@
cluster0.k0sop.mongodb.net/user?retryWrites=
true&w=majority`
Mongoose.connect(db, {
useNewUrlParser: true,
useUnifiedTopology: true,
useCreateIndex: true
}).then(() => console.log('MongoDB Connected....'))
// Handling GET /send Request
app.get("/send", async (req, res, next) => {
try {
let { page, size, sort } = req.query;
// If the page is not applied in query.
if (!page) {
// Make the Default value one.
page = 1;
}
if (!size) {
size = 10;
}
// We have to make it integer because
// query parameter passed is string
const limit = parseInt(size);
// We pass 1 for sorting data in
// ascending order using ids
const user = await User.find().sort(
{ votes: 1, _id: 1 }).limit(limit)
res.send({
page,
size,
Info: user,
});
}
catch (error) {
res.sendStatus(500);
}
});
// Handling POST /send Request
app.post('/send', jsonParser, (req, res) => {
req.body.password =
Bcrypt.hashSync(req.body.password, 10);
var newUser = new User({
username: req.body.username,
password: req.body.password,
})
newUser.save()
.then(result => {
console.log(result);
});
})
// Server setup
app.listen(3000, function () {
console.log("Express Started on Port 3000");
});
Step to Run Application: Run the application using the following command from the root directory of the project
node app.js
Output: Now open your browser and go to http://localhost:3000/send?sort, you will see the following output:
Sorting in descending order using IDs
// user.js
let mongoose = require("mongoose");
let userSchema = new mongoose.Schema({
username:String,
password:String
});
module.exports = mongoose.model("User", userSchema);
// app.js
let express = require('express'),
Mongoose = require('mongoose'),
Bcrypt = require('bcryptjs'),
bodyParser = require('body-parser'),
jsonParser = bodyParser.json(),
User = require('./user')
const app = express();
const db = `mongodb+srv://pallavi:pallavi123
@cluster0.k0sop.mongodb.net/user?
retryWrites=true&w=majority`
Mongoose.connect(db, {
useNewUrlParser: true,
useUnifiedTopology: true,
useCreateIndex: true
}).then(() => console.log('MongoDB Connected....'))
// Handling GET /send Request
app.get("/send", async (req, res, next) => {
try {
let { page, size, sort } = req.query;
// If the page is not applied in query
if (!page) {
// Make the Default value one
page = 1;
}
if (!size) {
size = 10;
}
// We have to make it integer because
// the query parameter passed is string
const limit = parseInt(size);
// We pass 1 for sorting data in
// descending order using ids
const user = await User.find().sort(
{ votes: 1, _id: -1 }).limit(limit)
res.send({
page,
size,
Info: user,
});
}
catch (error) {
res.sendStatus(500);
}
});
// Handling POST /send Request
app.post('/send', jsonParser, (req, res) => {
req.body.password =
Bcrypt.hashSync(req.body.password, 10);
let newUser = new User({
username: req.body.username,
password: req.body.password,
})
newUser.
save()
.then(result => {
console.log(result);
});
})
// Server setup
app.listen(3000, function () {
console.log("Express Started on Port 3000");
});
Step to Run Application: Run the application using the following command from the root directory of the project
node app.js
Output: Now open your browser and go to http://localhost:3000/send?sort, you will see the following output: