To test https://github.com/typicode/lowdb #Json #database #local #storage #localstorage #localdb

test.js

'use strict'

/* steps to use this test file: 
    1- install package lowdb : npm install lowdb
    2- create a file empty data.json
    3- manipulate the variable option to test the scenarios you want

*/


/** https://www.npmjs.com/package/lowdb */

const low = require('lowdb');
const FileSync = require('lowdb/adapters/FileSync');

const adapter = new FileSync('data.json'); // path and name of your local DB
const db = low(adapter);

//----------------------------------
    // I will use switch case to test scenarios below 
    var option = 3;  // Change this variable to test the scenarios you want
//----------------------------------

console.log(' ********************************* ');

switch(option) {
// option = 0 : create a obj. or a "table" named cities 
    case 0:
        console.log( '0 = ');
        console.log(
        db.defaults({ cities: []  })
        .write()
        );
        console.log(result);

      break;

// option = 1 : Insert a city in cities 'table' 
    // if exists update
    
    case 1:
        console.log( '1 = ');

        // test a city that already exists
        var objToInsert = {
            id : 1583326203652,
            cityName: 'São Paulo',
            state: 'SP'
        }

        // test a new city 
        var newCity = {
            "id": Date.now(),
            "cityName": "Itu",
            "state": "SP"
        }

        // query cities by ID
        if (db.get('cities').find({id : objToInsert.id}).value()){
            // when found update
            console.log(
                db
                .get('cities')
                .find({id:objToInsert.id})
                .assign({ 
                    cityName: objToInsert.cityName,
                    state: objToInsert.state
                })
                .write()
            );
        }else{
            // when NOT found insert
            console.log(
                db
                .get('cities')
                .push(newCity)
                .write()
            );
        }

    break;

// option = 2 : query a specific city 
    case 2:
        //2.1 cities that belong to state 'SP' (filter is the same as 'like' sql command here)
        if(
            db
            .get('cities')
            .filter({state: 'SP'})
            .value() 
        ){
            console.log( '2.1 = ');
            console.log(
                db
                .get('cities')
                .filter({state: 'SP'})
                .value() 
            );
        }

        //2.2  retrieve the FIRST object with the State = SP  
             
            console.log( '2.2 = ');
            console.log(db
                .get('cities')
                .find({state : 'SP'})
                .value() 
            );
            
    break;

// option = 3 : query all records from cities 'table'
    case 3:     
        result = db
        .get('cities')
        .filter({})
        .value()
        console.log('3 = ');
        console.log(result);
      break;

}