Question

我有一个包含大量嵌套回调的代码块。我对代码重构感兴趣，使其更具可读性并避免代码膨胀。有人可以提一下如何将以下代码转换为承诺。我想做一个比较，看看它是否值得在代码中应用promises的努力实现这样的代码回调

dataApi.getClientEntityByCtnId(Number(key), function (error, client1) {
    if (error) return callback(error, null);
    if (client1.id == 0)
        return callback("unregistered client:"+ key, null);
    dataApi.getClientEntityByCtnId(Number(key2), function (error, client2) {
        if (error)
            return callback(error, null);
        if (client2.id == 0)
            return callback("unregistered client:" + key2, null);

        dataApi.setClientRelationshipEntity(client1.id, client2.id, function (error) {
            if (error) return callback(error, null);                        
            dataApi.setClientRelationshipEntity(client2.id, client1.id, function (error) {
                nbCRpushed++;
                if (nbCRpushed%1000==0)  dataApi.logger.info("nb CR pushed into BC ="+nbCRpushed+"/" + dataApi.nbCR);
                if (error) return callback(error, null);

                if (nbCRpushed == dataApi.nbCR)
                {
                    dataApi.pushCRToCache(callback);
                }
            });
        });
    });
});

Answer 1

更喜欢 async / await ：

async function optimised(){
  var client1 = await dataApi.getClientEntityByCtnId(+key);
  if (client1.id == 0)
    throw new Error("unregistered client:"+ key);
 var client2 = await dataApi.getClientEntityByCtnId(+key2);
 if (client2.id == 0)
    throw new Error("unregistered client:" + key2);

 await dataApi.setClientRelationshipEntity(client1.id, client2.id);   
 await dataApi.setClientRelationshipEntity(client2.id, client1.id);   

 //i think the code below is broken now... more info needed to make it work asyncly
 nbCRpushed++;
 if (nbCRpushed%1000==0)  dataApi.logger.info("nb CR pushed into BC ="+nbCRpushed+"/" + dataApi.nbCR);
 if (nbCRpushed == dataApi.nbCR){
                dataApi.pushCRToCache(callback);//um callback? what should we do here??
}
}

可以这样：

optimised().then(function(){
   console.log("sucess");
},function(error){
  console.error(error);
});

请注意，所有dataApi方法都需要返回promises才能使其正常工作......

如何避免使用promises跟踪代码中的回调

1 个答案: