node.js + expressでjsonを使う例

あまり例を見かけなかったので、サンプルを動かした際のやり方をメモ。

特別なライブラリが不要ってのがうれしい。

以下は、Restful APIのイメージで、あるリクエストに対してサーバー側からブラウザ側にjsonでデータを送るケース。

/**
 * Module dependencies.
 */

var express = require('express');

var app = module.exports = express.createServer();

// Configuration

app.configure(function(){
  app.set('views', __dirname + '/views');
  app.set('view engine', 'jade');
  app.use(express.bodyParser());
  app.use(express.methodOverride());
  app.use(app.router);
  app.use(express.static(__dirname + '/public'));
});

app.configure('development', function(){
  app.use(express.errorHandler({ dumpExceptions: true, showStack: true })); 
});

app.configure('production', function(){
  app.use(express.errorHandler()); 
});

// Routes

app.get('/', function(req, res){
  res.render('index', {
    title: 'Express'
  });
});

app.get('/people.json', function(request, response) {
  // We want to set the content-type header so that the browser understands
  //  the content of the response.
  response.contentType('application/json');

  // Normally, the would probably come from a database, but we can cheat:
  var people = [
    { name: 'Dave', location: 'Atlanta' },
    { name: 'Santa Claus', location: 'North Pole' },
    { name: 'Man in the Moon', location: 'The Moon' }
  ];

  // Since the request is for a JSON representation of the people, we
  //  should JSON serialize them. The built-in JSON.stringify() function
  //  does that.
  var peopleJSON = JSON.stringify(people);

  // Now, we can use the response object's send method to push that string
  //  of people JSON back to the browser in response to this request:
  response.send(peopleJSON);
});

app.listen(3000);
console.log("Express server listening on port %d in %s mode", app.address().port, app.settings.env);

ポイントは"app.get('/people.json', function(request, response) {"から始まるブロック、ここでjsonの生成を実施しserializeを実行している。

これでnode.jsを起動させ、あとはブラウザで"http://localhost:3000/people.json"にアクセスする。

[{"name":"Dave","location":"Atlanta"},{"name":"Santa Claus","location":"North Pole"},{"name":"Man in the Moon","location":"The Moon"}]

成功！無事に値が取得できてる。