Node.js: mysql2 で MariaDB のデータを読む (Read)

プログラム

フォルダー構造

$ tree -a
.
├── .env
├── config_mariadb.js
├── go_read.sh
└── maria_read.js

Async/Await を使います。

maria_read.js

#! /usr/bin/node
// ---------------------------------------------------------------
//	maria_read.js
//
//					Feb/24/2024
//
// ---------------------------------------------------------------
'use strict'
var mysql = require('mysql2/promise')

var config_mariadb = require('./config_mariadb')
// ---------------------------------------------------------------
function compare_by_key_proc (left,right)
{
	var aa = left.key
	var bb = right.key

	var rvalue = 0

	if (aa < bb)
		{
		rvalue = -1
		}
	else if (aa > bb)
		{
		rvalue = 1
		}

	return	rvalue
}

// ---------------------------------------------------------------
function sort_key_proc (dict_aa)
{
	var array = new Array()

	for(var it in dict_aa)
		{
		array.push({'key':String (it), 'value':dict_aa[it]})
		}

	array.sort (compare_by_key_proc)

	return array
}

// ---------------------------------------------------------------
function dict_display_proc (dict_aa)
{
	const array_aa = sort_key_proc (dict_aa)

	array_aa.forEach (function(unit_aa,index)
		{
		const key = unit_aa.key
		const value = unit_aa.value

		var out_str = key + "\t"
		out_str += value["name"] + "\t"
		out_str += value["population"] + "\t"
		out_str += value["date_mod"]
		console.log (out_str)
		})	
}

// ---------------------------------------------------------------
async function read01 (mysql,host,user,password,data_base)
{
	try {
		var conn = await mysql.createConnection({
			host: host,
			user: user,
			password: password,
			database: data_base
			})
		const sql_str = 'select * from cities'
		const [rows, fields] = await conn.execute(sql_str)

		return rows
	} catch (ee) {
		console.log(ee)
		return ''
	} finally {
		if (conn && conn.connection) {
		conn.end()
		}
	}

}

// ---------------------------------------------------------------
async function main()
{
	const [host, user, password, data_base] = config_mariadb.config_mariadb_proc()
	const rows = await read01 (mysql,host,user,password,data_base)

	var dict_aa = new Object ()

	rows.forEach(function(row)
		{
		dict_aa[row.id] = {"name": row.name,
			"population": row.population,
			"date_mod": row.date_mod}
		})

	dict_display_proc (dict_aa)

	console.error ("*** 終了 ***")
}

// ---------------------------------------------------------------
console.error ("*** 開始 ***")
main()
// ---------------------------------------------------------------

.env
config_mariadb.py
はこちら
Node.js: MariaDB のバージョンを表示

実行コマンド

go_read.sh

export NODE_PATH=/usr/lib/node_modules
./maria_read.js

確認したバージョン

$ node -v
v19.7.0