# MogoDB

Reference

https://www.youtube.com/watch?v=ExcRbA7fy_A&list=PL4cUxeGkcC9h77dJ-QJlwGlZlTd4ecZOA

# Introduction

(No related Database)


- Collections (similar to tables)

- Documents (similar to records)

## Documents


A document is the data, similar to a JSON file. It can include other documents, creating relationships between them

# Installing MongoDB

Download MongoDB

https://www.mongodb.com/try/download/community




## Mongo DM compass (GUI)


## MongoDB Shell (CLI)



# Collection & Document

Database can have many collection

e.g. User collection, Post collection, Comment

- Collection


- Document


Documents appear as JSON object, but actually, the date is store as BSON (binary json)


## Nest Document


# MongoDB compass

## Connecting to MongoDB

### Local DataBase



### start_LOG

/local->start_log

Every time we start the DB, this action will be recording in the log file.

## Create Database




## Adding a document




A document can be represent as a JOSN object

When we want insert multiple documents, you can use an array [] to insert them.

 {
"gunname": "AK-47",
  "owner": "firearmlover",
  "price": 1200,
  "tags": [
    "rifle",
    "firearms"
  ],
  "rating": 8
 },
	{
  "gunname": "Glock 19",
  "owner": "gunenthusiast",
  "price": 600,
  "tags": [
    "handgun",
    "guns"
  ],
  "rating": 9
	},
  {
      "gunname": "Remington 870",
  "owner": "shootingpro",
  "price": 800,
  "tags": [
    "shotgun",
    "firearms"
  ],
  "rating": 7.5
  }
]


## Filter


# MongoDB shell

Fetch
Create
Delete
Update

PS C:\Users\USER> mongosh
Current Mongosh Log ID: 653b909bfcab94a7cf4c6659
Connecting to:          mongodb://127.0.0.1:27017/?directConnection=true&serverSelectionTimeoutMS=2000&appName=mongosh+1.10.6
Using MongoDB:          6.0.7
Using Mongosh:          1.10.6
mongosh 2.0.2 is available for download: https://www.mongodb.com/try/download/shell

For mongosh info see: https://docs.mongodb.com/mongodb-shell/

------
   The server generated these startup warnings when booting
   2023-10-20T15:41:17.416+08:00: Access control is not enabled for the database. Read and write access to data and configuration is unrestricted
------

### use {database}

test> show dbs
admin      40.00 KiB
config    108.00 KiB
gunShops   72.00 KiB
local      88.00 KiB
test>

test> use gunShops
switched to db gunShops

gunShops> use notExistsDB
switched to db notExistsDB

If the database does not exists, it will switch to a non-existent DB.

### DB

gunShops> db
gunShops

### show collections

gunShops> show collections
handgun

### Variable

gunShops> var name = "meowhecker"
gunShops> name
meowhecker

# Adding New Documents

gunShops> db
gunShops
gunShops> db.handgun  //database.collection
gunShops.handgun

## insertOne()

Syntax

database.collection.insertOne("JSON file")

{
 "gunname": "M4A1",
  "owner": "tacticalshooter",
  "price": 1500,
  "tags": [
    "rifle",
    "firearms"
  ],
  "rating": 9
}

gunShops> db.handgun.insertOne({"gunname": "M4A1","owner": "tacticalshooter","price": 1500,"tags": ["rifle","firearms"],"rating": 9})
{
  acknowledged: true,
  insertedId: ObjectId("653b985cfcab94a7cf4c665c")
}


## Inset document to non exists Collections

gunShops> db.admin.insertOne({"name":"meowhecker","age":18})
{
  acknowledged: true,
  insertedId: ObjectId("653b9ab7fcab94a7cf4c665d")
}

The monogoDB will automatic create the collection



## insertMany()

db -> current use database

db.collectionName.insertMany([{"key":"value"},{"key":"value"}])


# Finding Documents

find -> query

gunShops> db.handgun.find()

find method -> only show the 20 document, if want to show more have to type "it" to iterate it


## Filter

find(parameter 1,parameter 2,......)

parameter -> filter

gunShops> db.handgun.find({"owner":"meowhecker"})
[
  {
    _id: ObjectId("653b88c40aaa5623dde125b9"),
    gunname: 'P90',
    owner: 'meowhecker',
    price: 900,
    tags: [ 'handgub', 'guns' ],
    rating: 7
  }
]

### Multi-condition

gunShops> db.handgun.find({"rating": 9,"price":600})
[
  {
    _id: ObjectId("653b8b400aaa5623dde125bc"),
    gunname: 'Glock 19',
    owner: 'gunenthusiast',
    price: 600,
    tags: [ 'handgun', 'guns' ],
    rating: 9
  }
]

db.handgun.find({"rating": 9},{"gunname":1,"price":1})


gunShops> db.handgun.find({},{"gunname":1,"price":1})


## find single document by the object ID

db.handgun.find({_id:ObjectId("653b8b400aaa5623dde125bc")})


# Sorting & Limiting Data

## Count

gunShops> db.handgun.find({}).count()
5

## Limit


## Sort

db.handgun.find().sort({"price":1})


# Nested Documents

Insert


---


Insert

# Operators & complex queries

## query Operators

### great then ($gt

db.handgun.find({"rating":{$gt:8}})


### less then ($lt

db.handgun.find({"rating":{$lt:8}})


### grate/less equal ($lte

db.handgun.find({"rating":{$lte:8}})


## or Operator ($or)

or -> multi-condition

we have to use Array to do filter match

 db.handgun.find({$or:[{"rating":8},{"owner":"meowhecker"}]})


## And Operator ($and

gunShops> db.handgun.find({$and:[{"rating":{$gte:8}},{"price":{$lte:1000}}]})


## Using $in and $nin

gunShops> db.handgun.find({"rating":{$in:[7,9]}})


gunShops> db.handgun.find({"rating":{$nin:[7,9]}})


## $where

Match document satisfy the javascript expression

Syntax:

$where:javascript Expression

gunShops> db.handgun.find({$where:function(){return this.price === 1200}})
[
  {
    _id: ObjectId("653b8b400aaa5623dde125bb"),
    gunname: 'AK-47',
    owner: 'firearmlover',
    price: 1200,
    tags: [ 'rifle', 'firearms' ],
    rating: 8
  }
]

### Null byte

Null byte -> "%00"

db.admin.find({$where:function(){

    return this.username === "meowhecker" && this.password === "meowmeow"

}})

db.admin.find({$where:function(){return this.username === "meowhecker" && this.password === "meowmeow"}})


Using a Null byte to ignore the character after it (But it appears to work in old mongodb version)

gunShops> db.admin.find({ $where: function () {return this.username === 'meowhecker'\u0000' && this.password === 'meowmeow';}})
Uncaught:
SyntaxError: Invalid Unicode escape. (1:74)

> 1 | db.admin.find({ $where: function () {return this.username === 'meowhecker'\u0000' && this.password === 'meowmeow';}})
    |                                                                           ^
  2 

### $ne

"We can attempt to inject '$ne' into the password field to bypass authentication.

gunShops> db.admin.find({"username":"meowhecker","password":{$ne:"hacker"}})
[
  {
    _id: ObjectId("653b9ab7fcab94a7cf4c665d"),
    name: 'meowhecker',
    age: 18,
    password: 'meowmeow',
    superadmin: 1,
    username: 'meowhecker'
  }
]

# Querying Array

gunShops> db.handgun.find({tags:"rifle"})


## Restrict Match

gunShops> db.handgun.find({tags:["rifle","firearms"]})

## $all



## Retrieve sub document



# Delete Document

## deleteOne


gunShops> db.handgun.deleteOne({_id: ObjectId("653b985cfcab94a7cf4c665c")})
{ acknowledged: true, deletedCount: 1 }


## deleteMany()'

# Update Document

# $set


gunShops> db.admin.updateOne({ "name": "meowhecker"}, { $set: { "username": "meowhecker", "password": "meowmeow", "superadmin": 1 } })
{
  acknowledged: true,
  insertedId: null,
  matchedCount: 1,
  modifiedCount: 1,
  upsertedCount: 0
}

gunShops> db.admin.find()
[
  {
    _id: ObjectId("653b9ab7fcab94a7cf4c665d"),
    name: 'meowhecker',
    age: 18,
    password: 'meowmeow',
    superadmin: 1,
    username: 'meowhecker'
  }
]

## MongoDB drivers

Application(python,node)<--> MongoDB Drivers <--> MongoDB


## Node

npm init


touch app
npm install express --save 

Testing

const express = require('express')
const app = express()


app.listen(3000,()=>{
    console.log("meowhecker")
})


app.get('/gunshop',(req,res)=>{
    res.json({"message":"gun shop api"})
})

 nodemon app


## install mongoDB in node js

npm install mongodb --save 

# Connect to MongoDB

db.js

const { MongoClient } = require('mongodb')

let dbConnection

module.exports = {
  connectToDb: (cb) => {
    MongoClient.connect('mongodb://localhost:27017/gunShop')
      .then(client => {
        dbConnection = client.db()
        return cb()
      })
      .catch(err => {
        console.log(err)
        return cb(err)
      })
  },
  getDb: () => dbConnection
}

app.js

const express = require('express')
const app = express()

//import DB 
const {connectToDB,getDB} = require('./db')


//Connect to DataBase 
let db
connectToDB((err)=>{
    if (!err){
        app.listen(3000,()=>{
            console.log("meowhecker")
        })
        mongoDB = getDB()
    }
})




app.get('/gunshop',(req,res)=>{
    res.json({"message":"gun shop api"})
})


# Cursors & fetching Data

## app.js

const express = require('express')
const app = express()

//import DB 
const {connectToDB,getDB} = require('./db')


//Connect to DataBase 
let mongoDB
connectToDB((err)=>{
    if (!err){
        app.listen(3000,()=>{
            console.log("meowhecker")
        })
        mongoDB = getDB() // mongoDB = db(gunShop)
    }
})


app.get('/gunshop',(req,res)=>{
    let guns=[]
    // Find method will return a cursors . we have to use ForeEach to enumrate them(property)
    mongoDB.collection('handgun')
    .find()
    .sort({price:1})
    .forEach(gun => {
        guns.push(gun)
    }).then(()=>{
        res.status(200).json(guns)
    }).catch(()=>{
        res.status(500).json({error:"Could not to fetch documents"})
    })
    
    //res.json({"message":"gun shop api"})
})


# Finding single Document

app.get('/gunshops/:id', (req, res) => {
    console.log(req.params.id);
    const objectId = new ObjectId(req.params.id); // 轉換為有效的 ObjectId
    mongoDB.collection('handgun')
        .find({ _id: objectId }) 
        .toArray() // cursors to Arrat 
        .then((guns) => {
            res.status(200).json(guns);
        })
        .catch(() => {
            res.status(500).json({ "error": "Could not fetch the data" });
        });
});


Invalid Document ID

app.get('/gunshops/:id', (req, res) => {

    if(ObjectId.isValid(req.params.id)){
        console.log(req.params.id);
        const objectId = new ObjectId(req.params.id); 
        mongoDB.collection('handgun')
            .find({ _id: objectId }) 
            .toArray() 
            .then((guns) => {
                res.status(200).json(guns);
            })
            .catch(() => {
                res.status(500).json({ "error": "Could not fetch the data" });
            });
    }else {
        res.status(500).json({"error":"could not found the doc"})
    }

 
});


# Login Authentication

//Hard Code Database

const users = [
    { username: 'user1', password: 'password1' },
    { username: 'user2', password: 'password2' },
];


// Using body Parse to  Parse the pose request 
app.use(bodyParser.urlencoded({extended:true}))
app.use(bodyParser.json())


//Middle SoftWare
const authenticateUser = (req,res,next)=>{
    const {username,password} = req.body
    console.log(username,password)
    const user = users.find(u=>u.username === username && u.password===password)
    console.log(user)
    if (user){
        next();
    }else{
        res.status(401).json({error:"Authentication failed"})
    }
}

//loging EndPing 
app.post("/login",authenticateUser, (req,res)=>{
    console.log(1)
    res.status(200).json({Messages:"Authntication successful"})
})


Post Request

POST /login HTTP/1.1
Host: 127.0.0.1:3000
content-type:application/json
Connection: keep alive
Content-Length: 55

{
	"username": "user1", 
	"password": "password1" 
}