Steps to create node application And Installing Mongoose

Step 1: Create a node application using the following command:

mkdir folder_name
cd folder_name
npm init -y
touch main.js

Step 2: After creating the NodeJS application, Install the required module using the following command:

npm install mongoose

Project Structure: It will look like the following.

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

"dependencies": {
    "express": "^4.18.2"
}

Example 1: In this example, we will use a “required” validator to check whether a value is passed to the document or not before saving it to the DB.

Javascript

// main.js
 
const mongoose = require('mongoose')
 
// Database connection
mongoose.connect('mongodb://localhost:27017/query-helpers', {
    dbName: 'event_db',
    useNewUrlParser: true,
    useUnifiedTopology: true
}, err => err ? console.log(err) :
    console.log('Connected to database'));
 
const personSchema = new mongoose.Schema({
    name: {
        type: String,
        required: true
    }
});
 
const Person = mongoose.model('Person', personSchema);
const person = new Person({});
(async () => {
    try {
        await person.save();
    } catch (err) {
        console.log(err)
    }
})();

Step to Run Application: Run the application using the following command from the root directory of the project:

node main.js

Output:

Example 2: In this example, we will use a “required” and a “min” validator to check whether a value is passed to the document or not and whether the value is above a threshold number before saving it to the DB.

Javascript

// main.js
 
const mongoose = require('mongoose')
 
// Database connection
mongoose.connect('mongodb://localhost:27017/query-helpers', {
    dbName: 'event_db',
    useNewUrlParser: true,
    useUnifiedTopology: true
}, err => err ? console.log(err) :
    console.log('Connected to database'));
 
const personSchema = new mongoose.Schema({
    age: {
        type: Number,
        required: true,
        min: [18, 'Age must be 18 or above']
    }
});
 
const Person = mongoose.model('Person', personSchema);
const person = new Person({ age: 16 });
(async () => {
    try {
        await person.save();
    } catch (err) {
        console.log(err)
    }
})();

Step to Run Application: Run the application using the following command from the root directory of the project:

node main.js

Output:

Reference: https://mongoosejs.com/docs/validation.html

Mongoose Validation

Mongoose is a MongoDB object modeling and handling for a node.js environment. Mongoose Validation is essentially a customizable middleware that gets defined inside the SchemaType of Mongoose schema. It automatically fires off before a document is saved in the NoSQL DB. Validation can also be run manually using doc.validate(callback) or doc.validateSync() methods. Let’s understand more about this with the help of some examples.

Tags:

#Mongoose #Technical Scripter 2022 #Node.js #Technical Scripter #Web Technologies

2. Custom validators

Steps to create node application And Installing Mongoose

Javascript

Javascript

Mongoose Validation

Similar Reads