Nodejs Schema And Model Creation Complete Guide

Step 1: Setup Your Project

First, you need to set up a new Node.js project if you haven't done so already. Open your terminal and execute the following commands:

mkdir my-mongo-app
cd my-mongo-app
npm init -y
npm install mongoose

This will create a new directory my-mongo-app, navigate into it, initialize a Node.js project with default settings, and then install Mongoose in your project.

Step 2: Connect to MongoDB Database

Before creating schemas and models, we need to connect to our MongoDB database. We’ll use Mongoose to simplify this process.

Create a file named app.js and add the following code:

const mongoose = require('mongoose');

// Connection URI
const uri = 'mongodb://localhost:27017/mydatabase'; // Replace 'mydatabase' with your database name.

// Options for Mongoose connection
const options = {
    useNewUrlParser: true,
    useUnifiedTopology: true,
};

mongoose.connect(uri, options)
    .then(() => {
        console.log('Connected to MongoDB');
    })
    .catch((err) => {
        console.error('Connection error:', err);
    });

Make sure you have MongoDB installed and running on localhost:27017. You can also use MongoDB Atlas (a cloud-based version of MongoDB) by replacing the connection string with your own Atlas connection URI.

Step 3: Create Schema and Model

Let's create a simple schema for a User. In Mongoose, schemas are used to define the structure of documents stored in a collection. Models are built from schemas and allow us to perform CRUD operations.

Add the following code below the connection setup in app.js:

// Import Mongoose
const mongoose = require('mongoose');

// Define a User Schema
const userSchema = new mongoose.Schema({
    name: {
        type: String,
        required: true, // Name is a required field
        trim: true,     // Automatically trims whitespace
    },
    email: {
        type: String,
        required: true,
        unique: true,  // Email must be unique across all users
        match: [/.+\@.+\..+/, 'Please fill a valid email address'], // Email validation
        lowercase: true, // Converts email to lowercase before saving
        trim: true,
    },
    age: {
        type: Number,
        min: 0,         // Ensures age is not less than 0
        max: 125,       // Ensures age is not more than 125
    },
    createdAt: {
        type: Date,
        default: Date.now, // Defaults to the current timestamp when a new user is created
    },
    updatedAt: {
        type: Date,
        default: Date.now, // Defaults to the current timestamp when a user is updated
    }
});

// Pre-save middleware to update the `updatedAt` timestamp
userSchema.pre('save', function(next) {
    this.updatedAt = Date.now();
    next();
});

// Create User model
const User = mongoose.model('User', userSchema);

// Export the User model (optional, if you want to use it elsewhere)
module.exports = User;

Step 4: Use the Model

Now that we have a User model defined, let’s use it to create a new user in the database.

Add the following code at the end of app.js:

async function createUser() {
    try {
        const user = await User.create({
            name: 'Jane Doe',
            email: 'janedoe@example.com',
            age: 28
        });

        console.log('User created:', user);
    } catch (err) {
        console.error('Error creating user:', err.message);
    } finally {
        mongoose.connection.close(); // Close the connection once done
    }
}

createUser(); // Call the createUser function

The above code creates a new asynchronous function createUser that tries to create a new User document in the MongoDB collection using the defined User schema. If there are any validation errors or issues during the creation, they will be caught and logged. Finally, the database connection is closed.

Full Example

Here is the full app.js file with the complete steps:

const mongoose = require('mongoose');

// Connection URI
const uri = 'mongodb://localhost:27017/mydatabase'; // Replace 'mydatabase' with your actual database name.

// Options for Mongoose connection
const options = {
    useNewUrlParser: true,
    useUnifiedTopology: true,
};

mongoose.connect(uri, options)
    .then(() => {
        console.log('Connected to MongoDB');
    })
    .catch((err) => {
        console.error('Connection error:', err);
    });

// Define a User Schema
const userSchema = new mongoose.Schema({
    name: {
        type: String,
        required: true,
        trim: true,
    },
    email: {
        type: String,
        required: true,
        unique: true,
        match: [/.+\@.+\..+/, 'Please fill a valid email address'],
        lowercase: true,
        trim: true,
    },
    age: {
        type: Number,
        min: 0,
        max: 125,
    },
    createdAt: {
        type: Date,
        default: Date.now,
    },
    updatedAt: {
        type: Date,
        default: Date.now,
    }
});

// Pre-save middleware to update the `updatedAt` timestamp
userSchema.pre('save', function(next) {
    this.updatedAt = Date.now();
    next();
});

// Create User model
const User = mongoose.model('User', userSchema);

async function createUser() {
    try {
        const user = await User.create({
            name: 'Jane Doe',
            email: 'janedoe@example.com',
            age: 28
        });

        console.log('User created:', user);
    } catch (err) {
        console.error('Error creating user:', err.message);
    } finally {
        mongoose.connection.close(); // Close the database connection after the operation
    }
}

createUser(); // Call the createUser function

Running the Application

You can now run your application using:

node app.js

If everything is set up correctly, you should see a message indicating that you’re connected to MongoDB and then the details of the created user document.

Conclusion