Learn NodeJS

Create Project

$ mkdir sql-demo
$ cd sql-demo
$ npm init
$ npm install express --save
$ express
$ npm install

$ npm install sequelize --save
$ npm install mysql2 --save

database.js

const Sequelize = require('sequelize');

const db = new Sequelize("mytestdb", "root", "root",{ 
    host: 'localhost', 
    dialect:'mysql', 
    port:3306,
    pool: { max: 5, min: 0, idle: 10 * 1000 }
});

module.exports = db;

user.js

const db = require('./database');
const Sequelize = require('sequelize');

const user = db.define('user', {
  id: {
    type: Sequelize.BIGINT,
    allowNull: false,
    primaryKey: true,
    autoIncrement: true
  },
  uuid: {
    type: Sequelize.CHAR(36),
    allowNull: true,
    unique: true
  },
  username: {
    type: Sequelize.STRING(64),
    allowNull: false,
    defaultValue: '',
    unique: true
  },
  password: {
    type: Sequelize.STRING(255),
    allowNull: false,
    defaultValue: ''
  }
}, {
  timestamps: false,
  freezeTableName: true,
  tableName: 'user'
});

module.exports = user;

users.js

router.get('/:id', function (req, res, next) {
  var user1 = req.params.id;
  // create an async function
  let fn = async (user_id) => {
    let ret = await userModel.findOne({
      where: {
        id: user_id
      }
    })

    res.send(ret);
  }
  
  // call the async function
  fn(user1);
});

Create a table in mysql

user

NodeJS configuration file

Create sub folder config
Install nodejs config dependency package
```
$ npm install config --save
```

code to load from default.json

const config = require('config');
const { database, host, port, username, password } = config.sql;

create default.json inside the config folder for default configuration

{
  "sql": {
    "database": "mytestdb",
    "port": 3306,
    "host": "localhost",
    "username": "root",
    "password": "root"
  }
}

create production.json in the config folder for custom production configuration setting
```
{
  "sql": {
    "password": "root"
  }
}
```
Without setting environment variable, the custom configuration file will be chosen in the following order. Only parameter define in the custom file will be overwritten
1. local.json
2. development.json
3. production.json - need to set environment variable NODE_ENV=production

set environment variable NODE_ENV to load the production.json setting

// powershell
PS> $Env:NODE_ENV='production'

// cmd
D:/> set NODE_ENV=production

// linux
$ export NODE_ENV=production

// show environment variables
PS> dir env.

// show NODE_ENV setting
PS> $enc:NODE_ENV

create .env at root folder to set environment variable in a file

$ npm i dotenv

app.js to load the .env file

require('dotenv').config()

.env

# This will take production.json as configuration file
NODE_ENV=production

# This will take developemt.json as configuration file
NODE_ENV=development

# This set the config folder to `C:/home/config/wallet-api`
NODE_CONFIG_DIR=/home/config/wallet-api

Alternatively, overwrite default config folder programmatically

process.env["NODE_CONFIG_DIR"] = __dirname + "/configDir/";
const config = require("config");

VSCode debug

Reference

create launch.json in .vscode folder

Attach to process

{
  // Use IntelliSense to learn about possible attributes.
  // Hover to view descriptions of existing attributes.
  // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
  "version": "0.2.0",
  "configurations": [
    
    {
      "name": "Attach by Process ID",
      "processId": "${command:PickProcess}",
      "request": "attach",
      "type": "node"
    }]
 }

Debug single file

    {
      "name": "Debug current file",
      "program": "${file}",
      "request": "launch",
      "skipFiles": [
        "<node_internals>/**"
      ],
      "type": "node"
    }

Debug progam

   {
      "type": "node",
      "request": "launch",
      "name": "Launch Program",
      "skipFiles": [
        "<node_internals>/**"
      ],
      "program": "${workspaceFolder}\\bin\\www"
    }

Remote debugging

Reference

    {
      "address": "localhost",
      "localRoot": "${workspaceFolder}",
      "name": "Attach to Remote",
      "port": 9229,
      "remoteRoot": null,
      "request": "attach",
      "skipFiles": [
        "<node_internals>/**"
      ],
      "type": "node"
    },

run nodejs program. Don't run from vscode terminal. this will not work

$ node --inspect-brk ./bin/www

> node --inspect-brk ./bin/www

Debugger listening on ws://127.0.0.1:9229/dce127a4-322b-4a69-8f7c-2d60c94395de
For help, see: https://nodejs.org/en/docs/inspector

run vscode debugger Attach to Remote configuration

use ssh tunneling to map the remote address 9229 to localhost:9229

thyik/nodejs-sql-demo

Learn NodeJS

NodeJS configuration file

VSCode debug