MongoDB is an open-source document database that provides high performance, high availability, and automatic scaling. MongoDB obviates the need for an Object Relational Mapping (ORM) to facilitate development.

Mongo DB

MongoDB is a document database with the scalability and flexibility that you want with the querying and indexing that you need

Node js

Node.js is a platform built on Chrome’s JavaScript runtime for easily building fast and scalable network applications.
Using Mongoose we can connect MongoDB database and nodejs.

Mongoose

It is the Mongodb framework which is used to connect nodejs with mongodb database.

1) To install mongoose in nodejs use npm package: sh npm install mongoose

2) Link mongoose with Nodejs server: sh var mongoose = require('mongoose');

3) To connect a new MongoDB database: sh mongoose.connect('mongodb://localhost/database_name');

Create Model for collection

• Model - Models are used to create the fields of the documents.
  

Example :

var reg = mongoose.model('register',    //collection name
          {
              field1 : {type:String},         //string value
              field2 : {type:Number},         //number value
              field3 : {type: Object},            //json object value
              field4 : {type: Date},          //datetime value
              field5 : {type: Boolean},       //Boolean value true/false
              field6 : {type: String, required: true},    // string value must enter the value
              field7 : {type: Number, default: 0},    //number value    with default of '0' value
              field8 : {type: String, enum: ["active", "inactive","block"], default: "inactive"}, //string value which contain in enum array
              field9 : {type: Schema.Types.ObjectId, ref: 'modelName'}                       //object_id  of reference of another model
          });

To store the values into the mongodb server use the following syntax

Syntax :

objectname.save(function (err,data){
              //callback content
          });

Example :

var details = new reg(JSON_document);
          details.save(function (err,data) {    //insert to mongodb database
              if (err) {
                  console.log('Error block');
              } else {
                  console.log('Success block')
              }
          });

To Find data from the mongodb database use the following query
i) To get only one data from database use below syntax or example
ii) To get multiple data as array from database use below syntax or example

Syntax :

reg.findOne({},function(err,data){
              //callback content
          });

Example :

reg.findOne({key : value},function(err,data){
              res.send(data);     // send response 
          });

Syntax :

reg.find({},function(err,data){
              //callback content
          });

Example :

reg.find({key : value},function(err,data){
              res.send(data);     // send response 
          });

To Update data in mongodb database collection
i) Normal update
ii) Find and update

Syntax :

reg.update(QUERY_VALUE, UPDATE_VALUE).exec(function(err,value){
              if(err){
                  console.log("Error block")
              }else{
                  console.log("Success block")
              }
          });
          

Example :

reg.update({key:value}, {key1:value1,key2: value2}).exec(function(err,value){
              if(err){
                  console.log("Error block")
              }else{
                  console.log("Success block")
              }
          });
          

By default findOneAndUpdate returns the original document. If you want it to return the modified document pass an options object { new: true } to the function

Syntax :

reg.findOneAndUpdate({FIND_VALUE},{UPDATE_VALUE},{OPTIONAL}, 
            function(err, content){
              if(!err){
                  res.json({status: "success", data: value});
              }else{
                  res.json({status:"error"});
              }
          });

Example :

reg.findOneAndUpdate({key: value}, 
              {key1: value1, key2: value2}, {new: true}, function(err, doc){
              if(err){
                  console.log("Error block");
              }else{
                  console.log("Success block");
              }
          });

NOTE: if optional json contain {new:true} - it will return updated document details if optional json not contain or contain {new:false} - if will return old value

To delete a data collection from mongodb database:

i) Normal delete data from collection
ii) Find and remove data from collection
iii) Drop collection from mongodb database

Syntax :

reg.remove(QUERY_VALUE);

Example :

reg.remove({key:value});

reg.find({QUERY_VALUE}).remove().exec();

Example :

reg.find({key: value}).remove().exec();

syntax :

Collection_name.drop();

Example :

reg.drop();