如何将return一个值转入koa生成器？

Question

我有这样的东西：

var app = koa;

var run = function (generator){
  var it = generator(go);
  function go(err, res) {
    it.next(res);
  }
  go();      
}


app.use(function *() {
  run(function *(callback) {
     var result = yield asyncFunc(params, callback);
  });
  //I want to get value of result here;
});

那么如何用Koa构思得到这个值呢？

Answer 1

要获取函数的值，只需将其包装在 Promise 中

app.use(function *(){
 var promise = new Promise (function(resolve, reject){
   asyncFunc(params, function(err, res){
      if(err){reject(err)}
      else{resolve(res)}
   }
 }

 /*Added koa error handling example also*/
 try {
   var result = yield Promise
   // do what you want with result
 }
 catch{
   this.status = 500 // or 404, etc, whatever is appropriate
   /* the Koa docs have examples and go more in depth on error handling*/     
 }
}

此外，您不必自己运行（中间件）生成器，您也可以生成它们。这就是 Koa 的中间件链的全部内容

Answer 2

这是我找到的解决方案

var app = koa;

var foo = function(params) {
    return function(callback) {
        asyncFunc(params, function(err, result){
            if (err) callback(err);
            callback(null, result);
        });
    }
}

app.use(function *() {
  var result;
  try {
      result = yield foo(params);
  } catch {
      result = null;
  }
  console.log(result);
});

如何将return一个值转入koa生成器？

How to return a value into koa generator?

javascript

generator

callback

node.js

koa