readme.md

Data Modelling for Backend using Mongoose

Question should be what to store ? and not where to store the data, its format and fields?

• Tools

  • Professionaly : Moon Modeler :- MongoDB , NoSQL ; fields are given and automatically code is generated
  • Free Tier : eraser.io
    • use Diagram as a code > Entity Relationship
    • Open editor: code is available

• Overview

  • How data will be saved ; say for Login /Register page; Visulise on pen/paper
    • Registeration Page fields
      • username ; email ; password
      • $Protip💡$:only if there is another logic and how to store will all change so analyse all the required data need from user
      • dob ; photo

Let's Code

• Extra Tools

  • no need to install packages; online sites
    • github codespaces
    • replit
    • stackblitz

• go to stackblitz

  • select new and express
  • do npm i mongoose
  • $Protip💡$: maintain consistency ; standard followed nomenclature : - _ todo.models.js_

Models

• File structure

  • todos
    • todo.models.js
    • user.models.js
    • sub_todos.models.js

• Boilerplate code ; say write in user.models.js

import mongoose from 'mongoose'
const userSchema = new mongoose.Schema({
    // here all fields are defined
})
export const user User = mongoose.model("User" , userSchema)

• $Protip💡$:"User" gets converted to lowercase and plural : users
• write at line 2 : basic schema

const userSchema = new mongoose.Schema({
   username: String , 
   email : String , 
   isActive: Boolean
})

• Advanced schema ; unlocking the super power of mongoose

const userSchema = new mongoose.Schema({
   username: {
    type : String ,
    required : true  ,
    unique : true , 
    lowercase : true
   } , 
   password  :{
    // as reqd
   } , 
})

• Custom error messages : -
  • mini example:

  eggs: {
     type : Number , 
     min : [ 6 , `Must be atleast 6 got {value}`]
  }
  • use in user.models.js

const userSchema = new mongoose.Schema({
   username: {
    //as reqd
   } , 
   password  :{
    type : String ,
    required : [true  , "This field can not be empty"] ,
    unique : true , 
    lowercase : true
   } , 
})

• timestamps
  • {timestamps: true } will create two fields createdAt and updatedAt automatically

const userSchema = new mongoose.Schema({
   username: {
    //as reqd
   } , 
   password  :{
   // as reqd 
   } , 
   } , {timestamps: true })

• reference to other model

type: mongoose.Schema.Types.ObjectId,
ref: 'Hospital',

in sub_todos.js

createdBy:{
type: mongoose.Schema.Types.ObjectId,
ref: 'User'
}

• restricting choices
  • in order.models.js file

Status:{
   type:String , 
   enum : ["PENDING" ,  "CANCELLED" , "DELAYED"]
}

• $Protip💡$:instead of giving links of files like images , video (bulky data/buffer) , they are stored in a cloud service like cloudanary , AWS

Other Models

• Hospital Management
• ecommerce