server.js

//express js
var express = require('express');
var app = express();
var port = 3000;

//corse request
var cors = require('cors')
app.use(cors())

//enabling json body parse
app.use(express.json());

//MONGOOSE - requiring library
const mongoose = require('mongoose');

//auto increment sequence
var AutoIncrement = require('mongoose-sequence')(mongoose);

//MONGOOSE - connecting to database
mongoose.connect('mongodb://localhost:27017/pastebin',function(err){
    if(err){
        console.log("error occured while connecting to database");
    }else{
        console.log("successfully connected to database");
    }
});

//users schema
const UsersSchema = new mongoose.Schema({
    first_name: String,
    last_name: String,
    account_type: String,
    email: {
        type: String,
        unique: true,
        index: true
    },
    password: String
},{
    strict:false
});

//users model
const UsersModel = mongoose.model('users', UsersSchema,'users',{versionKey: false});

//users -> signup
app.post("/signup",(json_data,res)=>{
    //MONGOOSE - preparing json data for sending
    const new_signup = new UsersModel({first_name:json_data.body.first_name,
                                        last_name:json_data.body.last_name,
                                        account_type:json_data.body.account_type,
                                        email:json_data.body.email,
                                        password:json_data.body.password,
                                    });

    //MONGOOSE - inserting data to database
    new_signup.save(function (err, data) {
        if(err){
            if (err.code && err.code === 11000) {
                return res.json({status:3,msg:"Account Already Exists : "+json_data.body.email});    
            }
            return res.json({status:3,msg:"error occured while insertion "+err});
        }else{
            return res.json({status:1,msg:"account created successfully : "+json_data.body.email});
        }
    });
});

//pastes schema
const PastesSchema = new mongoose.Schema({
    user_id: String,
    private:Number,
    title: String,
    password: String,
    category: String,
    syntax: String,
    paste: String,
    url:String},{
      strict:false
});

//pastes model
const PastesModel = mongoose.model('pastes', PastesSchema,'pastes',{versionKey: false});

//pastes -> add
app.post("/pastes_add",(json_data,res)=>{
    //MONGOOSE - preparing json data for sending
    const new_paste = new PastesModel({ user_id:json_data.body.user_id,
                                        private:json_data.body.private,
                                        title:json_data.body.title,
                                        password:json_data.body.password,
                                        category:json_data.body.category,
                                        syntax:json_data.body.syntax,
                                        paste:json_data.body.paste,
                                        url:json_data.body.url
                                      });

    //MONGOOSE - inserting data to database
    new_paste.save(function (err, data) {
        if(err){
            return res.json({status:3,msg:"error occured while insertion "+err});
        }else{
            return res.json({status:1,msg:"paste added successfully : "+json_data.body.email});
        }
    });
});

//pastest -> gt
app.get("/pastes",(req,res)=>{
    //MONGOOSE - fetching data from database
PastesModel.find({url:req.query.url},function(err,data){
    if(data){
        //no data found
        if(data.length==0){
            res.json({
                'status':0,
                'data':data
            })
        }else{
            //data found
            res.json({
                'status':1,
                data:data
            })
        }
    }
    //if error occured than send status code 3
    if(err){
        res.json({
            status:3,
        })
    }

    
});
});

//listing express
app.listen(port, () => {
    console.log(`Example app listening on port ${port}`)
})