Question

我是节点js中的新手，我在节点js中使用Promise中间件。但我没有发现它的文档对我有用，也无法理解如何在一个请求中使用两个回调，或者如何使用多个回调。请帮助我。

这是我的代码

//get application types
var p1 = new Promise(function(resolve, reject) {
  console.log("in p1");
  var url = tURL+'applicationType/getAll'
  var args = {
    headers:{"AuthKey": req.session.name}
  };
  client.get(url, args, function(data,response) {
      console.log(data, "in get all app type req");
      if(data.status == "success"){
        return resolve(data);
      }
      else{
        reject ("unamble to get data!")
      }
  });
});

p1.then(function(data) {
  console.log(data.response.applicationType, "in p1 then", data)
  //load page after data
  res.render('app', {
    message: req.session.name,
    uName: "THE MECHANIC",
    applist: data.response.applicationType
  });
},function(reason) {
  console.log(reason, "reason in not then"); // Error!
});



//get all application
var p2 = new Promise(function(resolve, reject){
  console.log("in p2");
  var url = tURL+'applications'
  var args = {
    headers:{"AuthKey": req.session.name}
  };
  client.get(url, args, function(data,response) {
      console.log(data, "in get app req");
      if(data.status == "success"){
        return resolve(data);
      }
      else{
        reject ("unamble to get data!")
      }
  });
});

p2.then(function(data) {
  console.log(data.response, "in p2 then", data)
  //load page after data
  res.render('app', {
    appList: data.response
  });

},function(reason) {
  console.log(reason, "reason in not p2"); // Error!
});

寻找解决方案 在请求完成后，我必须在页面上发送数据。 2.如何使用render或任何其他方式管理对象中的响应并将其发送到页面？

Answer 1

我的第一个建议是找到一种以原生方式宣传client.get的方法，我不确定它代表什么样的lib，并且它不遵循节点样式的回调为fun(err, data)，除此之外，我假设，您对服务器有一个请求，您将多个请求发送到其他地方，然后捆绑所有响应并回复请求者权利？

我会重构像

这样的代码

function pGet(url, args){
  return new Promise(function(resolve, reject){
    client.get(url, args, function(data, response){
      if(data.status === 'success') resolve(data);
      else reject('unable to get data');
    });
  });
}

router.get('/api/someAPI', function(req, res, next){
  var resultJSON = {
    message: req.session.name,
    uName: "THE MECHANIC"
  }, args = { headers:{"AuthKey": req.session.name} },
  p1, p2;

  p1 = pGet(tURL+'applicationType/getAll', args)
    .then(function(data){
      resultJSON.applist = data.response.applicationType;
    }).catch(console.log.bind(console));

  p2 = pGet(tURL+'applications', args)
    .then(function(data){
      resultJSON.appList = data.response;
    }).catch(console.log.bind(console));

  // now we send the response once both of the promises finish
  Promise.all([p1, p2]).then(function(){
    res.render('app', resultJSON); 
  }); // not adding any error handler since both the previous ones should not throw any.

});

在节点js回调函数中承诺中间件如何使用多个呢？

1 个答案: