Default Value in MongoDB using Node.js

Last Updated : 08 Jan, 2025

Setting default values in MongoDB using Node.js can streamline the database management process by ensuring that certain fields always have an initial value even if they are not provided by the user. This practice is particularly useful for maintaining data integrity, setting fallback values, and simplifying the data insertion process. This guide will walk you through how to set default values in MongoDB when using Node.js, focusing on both the Mongoose ODM (Object Data Modeling) library and MongoDB’s native driver.

Why Set Default Values?

Data Integrity: Ensure that essential fields always have a value.
Simplify Code: Reduce the need for manual default setting in your application logic.
Consistency: Maintain consistent data structures across your database.

Using Mongoose

Mongoose is a popular ODM library for MongoDB that provides a straightforward way to define schemas, models, and default values. Below, we’ll explore how to set up default values in Mongoose.

Default Value

This value is entered when no value is entered as a value of the field in the collection.

Installation Steps

Step 1: Make a folder structure for the project.

mkdir GFG

Step 2: Navigate to the project directory

cd GFG

Step 3: Initialize the NodeJs project inside the GFG folder.

npm init -y

Step 4: Install the required dependencies by the following command:

npm install mongoose

Project Structure

The updated dependencies in package.json file will look like:

"dependencies": {
    "mongoose": "^8.4.4",
  }

Running the server on Local IP: Data is the directory where MongoDB server is present.

mongod --dbpath=data --bind_ip 127.0.0.1

Example: Implementation to show the default value in MongoDB using NodeJs.

JavaScript

// app.js

// Importing mongoose module
const mongoose = require("mongoose");

// Database Address
const url = "mongodb://localhost:27017/GFG";

// Connecting to database
mongoose
  .connect(url)
  .then((ans) => {
    console.log("Connected Successful");
  })
  .catch((err) => {
    console.log("Error in the Connection");
  });

// Schema class
const Schema = mongoose.Schema;

// Creating Structure of the collection
const collection_structure = new Schema({
  name: {
    type: String, // String type
    required: true,
  },
  marks: {
    type: Number, // Number type
    default: 100,
  },
});
// Creating collection
const collections = mongoose.model("GFG2", collection_structure);

// Inserting one document
collections
  .create({ 

    // Inserting value of only one key
    name: "aayush",
  })
  .then((ans) => {
    console.log(ans);
  })
  .catch((err) => {
    console.log(err.message);
  });