NodeJS异步:已经调用了回调? [英] NodeJS Async: Callback already called?

问题描述

我在Node.JS中使用Async模块来跟踪我的异步调用.但是，我收到一个错误-已调用回叫." 有人可以帮我吗?

I'm using Async module in Node.JS to keep track of my asynchronous calls. However, I'm getting an error - "Callback already called." Can someone help me out here?

async.each(data['results'], function(result, done) { 
    if (result['twitter_id'] !== null) { //Isolate twitter handle
        var param = { "user.screen_name": result['twitter_id']}
        db.test4.find( param, function(err, users) {
            if( err ) {
                return done(err);
            } else if (!users) {
                res.send("No user found");
            } else {
                users.forEach( function(Result) { 
                    twitter_ids.push(Result);
                    //console.log(Result);
                    done();
                });
            }
        });
    }
}, function(err) {  
    if (err) {
        throw err
    }
    res.send(twitter_ids);
});

推荐答案

您正在调用res.send(找不到用户");每次您加载失败.但是，您可能无法多次加载.

You're calling res.send("No user found"); each time you fail to load. However you can fail to load multiple times.

解决方案是将所有响应代码放入最终回调中，而不是每个回调中.

The solution is to put all your response code in the final callback, not in the each callback.

async.each(data['results'], function(result, done) { 
    if (result['twitter_id'] !== null) { //Isolate twitter handle
        var param = { "user.screen_name": result['twitter_id']}
        db.test4.find( param, function(err, users) {
            if( err ) {
                done(err);
            } else if (!users) {
                done(new Error("No user found"));
            } else {
                users.forEach( function(Result) { 
                    twitter_ids.push(Result);
                    //console.log(Result);
                });
                done();
            }
        });
    } else {
      done();
    }
}, function(err) {  
    if (err) {
        return next(err);
    }
    res.send(twitter_ids);
});

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