CRUD - MongoDB

This article contains the basics of MongoDB. A no-SQL database that stores your data in the form of the collection like Tables in SQL.

REQUIREMENT

1. Basic Javascript - Promises, Error handling
2. CMD
3. ROBO3T GUI
4. Your Native mongodb must be running.

Install -

1. npm install mongodb

Then create a file(any_name.js) inside a Folder(Any_name):

Then inside of your "any_name.js" file :

const MongoDB = require("mongodb");
const MongoClient = MongoDB.MongoClient;

const databaseName = "first-project";
const connectionUrl = 'mongodb://127.0.0.1:27017';

MongoClient.connect(connectionUrl, { useUnifiedTopology: true }, (err, client) =>{
if(err){
console.log(errr)
}

This creates a database automatically

const db = client.db(databaseName);

INSERTION

INSERTION ONE

  db.connection("User").insertOne({
  name: "Saurabh",
  age: 21
  }).then((error) =>{
  console.log(error)
  }).catch((result) =>{
  console.log(result)
  })

INSERTION MANY

    db.connection("User").insertMany([
    {
    name: "Saurabh",
    age: 21
    },
    {
    name: "Gaurav",
    age: 21
    }

    ]).then((error) =>{
    console.log(error)
    }).catch((result) =>{
    console.log(result.ops)
    })

.ops -> Is used to give you an array. This is not generally used in case of insertOne as it only gives you only one object. This is generally used in Case of insertMany

READ

findOne is used to find a particular data and find is used to to extract multiple data -> Here we can use different methods. Like - toArray(), count etx.

db.collection('Task').findOne({
     age: 12
}).then((output) =>{
   console.log(output)
}).catch((error) =>{
    console.log(error)
})

db.collection('User').find({age:45}).toArray((error, result) =>{
    console.log(result)
})

UPDATE

Here, we use updateOne to update a particular value. And $set it takes a new value that we want in place of the previous data.

db.collection('User').updateOne({
    name:"Saurabh Kumar"
},{
   $set: {
       name: "Gaurav Kumar"
   }
}).then((result) =>{
    console.log(result)
}).catch((error) =>{
    console.log(error)
})

DELETE

Here, we use deleteMany. And in the below wxample we put a constraint that is Age.

db.collection('User').deleteMany({
    age: 45
}).then((result) => {
    console.log(result.ops)
}).catch((error) => {
    console.log(error)
})

})

Hope you like it :D

For more you can visit over here -

http://mongodb.github.io/node-mongodb-native/3.5/api/Collection

Complete Code over here -

https://github.com/skwebdeveloper/CRUD_Basics_MongoDB

Comments

[Shravan Kumar B]

You mentioned we need to install express.js; which is not required if you are just running this DB file. And the whole code can be written in much better way. What you have written in callback pattern of coding.

Now you have Promises and Async - Await Pattern to handle asynchronous operations.
If you want, I can work on this file and make a cleaner code.

:)

[Saurabh Kumar]

Ya sure. If you want to make it a bit clear then it's most welcomed. And I just want to make it clear that this is just for beginners. So, I don't want to confuse them by adding Async and Await. Thanks for your suggestions. And yes Express is not needed :D.