在Express render()中为函数调用获取未定义

时间:2014-12-16 09:22:51

标签: javascript node.js asynchronous express

我是Node和Express的新手,在从一个函数获取数据时遇到麻烦,以var作为另一个函数传递。我认为这是因为我没有正确处理回调和异步的东西,但是我会很感激。“

希望代码可以解释。我试图从URL中检索一些JSON数据,并将其传递给router.get函数的render()方法。但是,不会发送任何内容(“未定义”)。但是,当我单独运行getData()函数时,它返回正确的数据,如上所述,我认为这是因为我没有正确处理异步内容。

function getData(cid){
   var request = require("request");
   var cid ='XXXXXX' // hard code temp
   var baseUrl = "someurl.com"
   var apiKey = "XXXXXX"
   var cUrl = baseUrl+cid+'?api_key='+apiKey


  request({
    url: cUrl,
    json: true
  }, function (error, response, body) {

    if (!error && response.statusCode === 200) {
      console.log(body._embedded.assets); //Print the json response
      return body._embedded.assets
    }
  });
}

/* GET home page. */
router.get('/', function(req, res) {

  var LiveCards = getData()
  var cID = (req.query.cID
            ? req.query.cID
            : '14d115ff-1db7-4a6f-8648-ea64bc1a6597')
  var limit = Number(req.query.limit)

  res.render('index', {
      title: 'Cards',
      cards: LiveCards.slice(0,limit), <--- returning undefined at the moment
      limit: limit,
      activateSharetools: activateSharetools,
      cID: cID,
      cardsHeader: req.query.cardsHeader,
   });
});

任何指导意见。

1 个答案:

答案 0 :(得分:1)

请求是异步函数,您需要添加回调以获取数据并在完成请求后执行它,如下所示:

function getData (cid, callback) {
   var request = require("request");
   var cid     = 'XXXXXX';
   var baseUrl = "someurl.com";
   var apiKey  = "XXXXXX";
   var cUrl    = baseUrl + cid + '?api_key=' + apiKey

  request({url: cUrl, json: true}, callback);
}

router.get('/', function (req, res) {
  var cID   = req.query.cID ? req.query.cID : '14d115ff-1db7-4a6f-8648-ea64bc1a6597');
  var limit = Number(req.query.limit);

  getData(cID, function (error, response, body) {
    if (!error && response.statusCode === 200) {
      res.render('index', {
        title: 'Cards',
        cards: body._embedded.assets.slice(0, limit), <--- returning undefined at the moment
        limit: limit,
        activateSharetools: activateSharetools,
        cID: cID,
        cardsHeader: req.query.cardsHeader,
      });
    } else {
      throw error;
    }
  });
});