node js中的promise中间件回调函数如何使用多个呢？

Question

我是 node js 的新手，我在 node js 中使用 Promise 中间件。但是我没有发现它的文档对我有用并且无法理解如何在一个请求中使用两个回调或者应该如何使用多个。请帮助我谢谢。

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!
});

正在寻找解决方案 1.我必须在两个请求完成后在页面上发送数据。 2. 如何管理对象中的响应并使用 render 或任何替代方法将其发送到页面？

Answer 1

我的第一个建议是找到一种以原生方式 promisify client.get 的方法，我不确定它代表什么库，并且它不遵循节点式回调 fun(err, data) ，除此之外，我假设，您对您的服务器有一个请求，您将多个请求发送给其他东西，然后捆绑他们的所有响应并响应请求者，对吧？

我会像这样重构代码

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.

});

node js中的promise中间件回调函数如何使用多个呢？

Promise middleware in node js callback functions how to use multiple then?

javascript

middleware

node.js

promise