{"id":73335,"date":"2020-01-15T16:44:42","date_gmt":"2020-01-15T11:14:42","guid":{"rendered":"https:\/\/www.vskills.in\/certification\/tutorial\/?p=73335"},"modified":"2024-04-12T14:27:14","modified_gmt":"2024-04-12T08:57:14","slug":"mongoose-2","status":"publish","type":"page","link":"https:\/\/www.vskills.in\/certification\/tutorial\/mongoose-2\/","title":{"rendered":"Mongoose"},"content":{"rendered":"\n

Go back to Tutorial<\/a><\/p>\n\n\n

Mongoose is a MongoDB object modeling tool designed to work in an asynchronous environment.<\/p>\n

Installation<\/strong><\/p>\n

First install node.js and mongodb. Then:<\/p>\n

$ npm install mongoose<\/p>\n

Connecting to MongoDB<\/strong><\/p>\n

First, we need to define a connection. If your app uses only one database, you should use mongoose.connect. If you need to create additional connections, use mongoose.createConnection.<\/p>\n

Both connect and createConnection take a mongodb:\/\/ URI, or the parameters host, database, port, options.<\/p>\n

const mongoose = require(‘mongoose’);<\/p>\n

mongoose.connect(‘mongodb:\/\/localhost\/my_database’);<\/p>\n

Once connected, the open event is fired on the Connection instance. If you’re using mongoose.connect, the Connection is mongoose.connection. Otherwise, mongoose.createConnection return value is a Connection.<\/p>\n

If the local connection fails then try using 127.0.0.1 instead of localhost. Sometimes issues may arise when the local hostname has been changed. Mongoose buffers all the commands until it’s connected to the database. This means that you don’t have to wait until it connects to MongoDB in order to define models, run queries, etc.<\/p>\n

Defining a Model<\/strong><\/p>\n

Models are defined through the Schema interface.<\/p>\n

const Schema = mongoose.Schema;<\/p>\n

const ObjectId = Schema.ObjectId;<\/p>\n

const BlogPost = new Schema({<\/p>\n

author: ObjectId,<\/p>\n

title: String,<\/p>\n

body: String,<\/p>\n

date: Date<\/p>\n

});<\/p>\n

Aside from defining the structure of your documents and the types of data you’re storing, a Schema handles the definition of:<\/p>\n