What are CRUD operations in MongoDB?

MongoDB, a popular NoSQL database, operates using documents (usually in a JSON-like format known as BSON) and collections instead of the typical rows and tables in relational databases. One of the fundamental aspects of using any database is the ability to Create, Read, Update, and Delete data – commonly referred to as CRUD operations. In MongoDB, these operations can be executed with a variety of methods.

In this guide, we will delve into each CRUD operation in MongoDB, and you’ll learn how to effectively use them.

C - Create

Creating, or inserting, data is the act of adding new documents to a collection in MongoDB.

Insert One Document

To add a single document, you can use the insertOne method.

const MongoClient = require('mongodb').MongoClient;

const url = 'mongodb://localhost:27017';
const dbName = 'mydatabase';

MongoClient.connect(url, function(err, client) {
    const db = client.db(dbName);
    const collection = db.collection('documents');
    collection.insertOne({
        name: 'John Doe',
        age: 30
    }, function(err, result) {
        console.log('Inserted document');
        client.close();
    });
});

Insert Multiple Documents

If you have multiple documents, the insertMany method is more suitable.

const documents = [{
    name: 'Alice',
    age: 28
}, {
    name: 'Bob',
    age: 25
}];

collection.insertMany(documents, function(err, result) {
    console.log('Inserted documents');
    client.close();
});

R - Read

Reading, or querying, data involves retrieving documents from a collection based on certain criteria.

Find One Document

To get a single document that matches a condition:

collection.findOne({name: 'John Doe'}, function(err, document) {
    console.log(document);
});

Find Multiple Documents

To retrieve multiple documents:

collection.find({age: {$gt: 25}}).toArray(function(err, documents) {
    console.log(documents);
});

In this example, we’re using the $gt operator to find all documents where the age is greater than 25.

U - Update

Updating involves modifying existing documents in a collection.

Update One Document

To update a single document:

collection.updateOne({name: 'John Doe'}, {$set: {age: 31}}, function(err, result) {
    console.log('Updated document');
});

Here, we’re using the $set operator to modify the age of John Doe.

Update Multiple Documents

To update multiple documents:

collection.updateMany({age: {$lt: 30}}, {$set: {status: 'young'}}, function(err, result) {
    console.log('Updated documents');
});

D - Delete

Deleting is the removal of documents from a collection.

Delete One Document

To remove a single document:

collection.deleteOne({name: 'John Doe'}, function(err, result) {
    console.log('Deleted document');
});

Delete Multiple Documents

To remove multiple documents:

collection.deleteMany({age: {$lt: 30}}, function(err, result) {
    console.log('Deleted documents');
});

Conclusion

CRUD operations form the backbone of many applications, allowing for effective data management. With MongoDB’s versatile methods and easy-to-understand syntax, performing CRUD operations is both straightforward and efficient.

Remember, while these examples demonstrate the basic usage of CRUD operations, MongoDB offers a wide range of querying and updating capabilities, including complex aggregations and atomic operations. Always refer to the official MongoDB documentation for a deep dive into advanced features and best practices.