Express で簡単な WebAPI を作成

必要なライブラリーのインストール

sudo npm install -g express
sudo npm install -g cfenv

サーバープログラム

フォルダー構造

$ tree
.
├── app.js
└── routes
    └── index.js

app.js

//-------------------------------------------------------------------------
//	app.js
//
//					May/24/2023
//-------------------------------------------------------------------------
const express = require('express')
const routes = require('./routes')
const cfenv = require('cfenv')

var app = express()
app.use(express.json())
app.use(express.urlencoded({ extended: true }));

app.use(express.static(__dirname + '/public'))

var appEnv = cfenv.getAppEnv()

app.post('/post_test',routes.post_test)

app.listen(appEnv.port, '0.0.0.0', function() {
  console.log("server starting on " + appEnv.url)
})

//-------------------------------------------------------------------------

routes/index.js

// -----------------------------------------------------------------------
/*
	routes/index.js

						Jan/18/2020
*/
// -----------------------------------------------------------------------
exports.post_test = function(req,res)
{
	var aa = 0
	var bb = 0

	if (req.body.aa) {
		aa = parseInt(req.body.aa,10)
		}

	if (req.body.bb) {
		bb = parseInt(req.body.bb,10)
		}

	var dict_aa = {}
	dict_aa["aa"] = aa
	dict_aa["bb"] = bb
	dict_aa["sum"] = aa + bb
	dict_aa["diff"] = aa - bb

	var str_out = JSON.stringify(dict_aa)

	res.send(str_out)
}

// -----------------------------------------------------------------------

サーバーの起動

$ export NODE_PATH=/usr/lib/node_modules
$ node app.js 
server starting on http://localhost:3000

curl のテストスクリプト

go_test.sh

#
URL=http://localhost:3000/post_test
#
curl -X POST -d aa="12" -d bb="45" $URL
#
echo
#
curl -X POST -H "Content-Type: application/json" \
	-d '{"aa":"32", "bb":"41"}'  $URL
#
echo
#
curl -X POST -H "Content-Type: application/json" \
	[e-mail] $URL
#
echo
#

in01.json

{"aa":"52", "bb":"84"}

実行結果

$ ./go_test.sh 
{"aa":12,"bb":45,"sum":57,"diff":-33}
{"aa":32,"bb":41,"sum":73,"diff":-9}
{"aa":52,"bb":84,"sum":136,"diff":-32}

HTTPie のテストスクリプト

go_http.sh

URL=http://localhost:3000/post_test
#
http POST $URL aa="12" bb="45"
#
echo
#
echo '{"aa":"32", "bb":"41"}' | http POST $URL
#
echo
#
http POST $URL < in01.json
#
echo
#

確認したバージョン

$ node --version
v20.2.0

$ npm info express version
4.18.2