How to Pull Item from an Array in Mongoose ?
In Mongoose, pulling an item from an array can be done using several methods. To pull an item from an array, you can use the $pull operator along with the updateOne() or updateMany() method.
We will discuss the different methods to pull items from an array in Mongoose
Table of Content
- Using $pull Operator
- Pull Based on a Condition
- Pull from Nested Arrays
- Using the $pop Operator
Steps to Create the Application
Step 1: Make a folder named ‘mongodb-example’ and navigate to it using this command.
mkdir mongodb-example
cd mongodb-example
Step 2: Install modules as per requirements.
npm install express mongoose
Project StructureProject Structure
Project Structure
Updated Dependencies in your package.json file
"dependencies": {
"express": "^4.19.2",
"mongoose": "^8.3.4"
}
Example: This code is of server.js file which is same for all approaches example code and ‘app.js’ is inserting sample document for performing all example code.
// Filename - Server.js
const mongoose = require('mongoose')
const DB_URI = 'XXXX-XXX'
function dbConnection() {
mongoose.connect(DB_URI)
console.log('Database connected successfully.')
}
const productSchema = new mongoose.Schema({
name: String,
price: Number,
categories: [String],
reviews: [{
reviewer: String,
rating: Number,
comment: String
}]
});
const Product = mongoose.model('Product', productSchema);
module.exports = {
dbConnection,
Product
}
// app.js
const express = require('express')
const app = express();
const PORT = 8000;
const { Product, dbConnection } = require('./server')
dbConnection(); // connecting to database
async function inserting() {
const newProduct = new Product({
name: 'Laptop',
price: 999.99,
categories: ['Electronics', 'Computers'],
reviews: [
{ reviewer: 'sandy', rating: 5, comment: 'Great laptop!' },
{ reviewer: 'nakul', rating: 4, comment: 'Good value for money.' },
{ reviewer: 'jatin', rating: 3, comment: 'Loving Product.' },
{ reviewer: 'mukesh', rating: 2, comment: ' Decent.' },
{ reviewer: 'mohan', rating: 0, comment: 'no value.' }
]
});
await newProduct.save()
console.log('Item inserted successfully.')
}
inserting()
// server listening
app.listen(PORT, () => {
console.log(`Server is running on ${PORT}`)
})
Output:
MongoDB Output
Using $pull Operator
To remove a specific value from an array, employ the $pull operator with the targeted ( to be removed ) value.
Example:
// Filename - app.js
const express = require('express')
const app = express();
const PORT = 8000;
const { Product, dbConnection } = require('./server')
dbConnection(); // connecting to database
async function pulling(productId, categoryToRemove) {
const result = await Product.updateOne(
{ _id: productId },
{ $pull: { categories: categoryToRemove } });
console.log('Category removed:', result);
}
pulling('664491772960d488ab55a620', 'Electronics')
// server listening
app.listen(PORT, () => {
console.log(`Server is running on ${PORT}`)
})
Output:
$Pull Operator Output
Pull Based on a Condition
Here you have one or more queries and you remove elements based on that queries by any method like $pull operator or custom logic.
Example:
// Filename - app.js
const express = require('express')
const app = express();
const PORT = 8000;
const { Product, dbConnection } = require('./server')
dbConnection(); // connecting to database
async function pulling(productId) {
const result = await Product.updateOne(
{ _id: productId },
{ $pull: { reviews: { rating: { $lt: 4 } } } },
);
console.log('Reviews removed:', result);
}
pulling('664491772960d488ab55a620')
// server listening
app.listen(PORT, () => {
console.log(`Server is running on ${PORT}`)
})
Output:
$Pull On Condition Output
Pull from Nested Arrays
Pulling from nested arrays involves using the $pull operator with dot notation to specify the nested array path. You can also remove elements based on conditions within the nested array.
Example:
// app.js
const express = require('express')
const app = express();
const PORT = 8000;
const { Product, dbConnection } = require('./server')
dbConnection(); // connecting to database
async function pulling(productId, reviewer) {
const result = await Product.findByIdAndUpdate(productId,
{ $pull: { reviews: { reviewer } } });
console.log('Review by reviewer removed:', result);
}
pulling('664491772960d488ab55a620', 'nakul')
// server listening
app.listen(PORT, () => {
console.log(`Server is running on ${PORT}`)
})
Output:
$Pull from Nested Array Output
Using the $pop Operator
The $pop operator removes the first(-1) or last (1 ) element from an array.
Example:
// Filename - app.js
const express = require('express')
const app = express();
const PORT = 8000;
const { Product, dbConnection } = require('./server')
dbConnection(); // connecting to database
async function pulling(productId ) {
const result = await Product.findByIdAndUpdate(productId,
{ reviews: { $pop: { reviewer: -1 } } });
console.log('Review by reviewer removed:', result);
}
pulling('664491772960d488ab55a620' )
// server listening
app.listen(PORT, () => {
console.log(`Server is running on ${PORT}`)
})
Output:
$Pop Operator Output
Using Custom Logic
It involves manually retrieving the document, modifying the array using JavaScript, and then saving the modified document to the database.
Example:
// Filename - app.js
const express = require('express')
const app = express();
const PORT = 8000;
const { Product, dbConnection } = require('./server')
dbConnection(); // connecting to database
async function pulling(productId, elementToRemove) {
const product = await Product.findById(productId);
product.reviews = product.reviews.filter(item => item.reviewer !== elementToRemove);
await product.save();
console.log('Review by reviewer removed:', product);
}
pulling('66449c28c1c05b5eccf8071a', 'jatin')
// server listening
app.listen(PORT, () => {
console.log(`Server is running on ${PORT}`)
})
Output:
Custom Logic Output
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