Question

我只是做了我的第一个Node异步内容，我想对DB进行两次查询，然后依次打印结果，我的代码如下：

console.log(req.query);

function logAllThings(err,things){
    if (err){
        console.log(err);
    } else {
        console.log(things);
    };
};


async.parallel([
    function(callback) { //This is the first task, and callback is its callback task
        Event.find({}, function(err, events) {
            logAllThings(err,events);
        });
    },
    function(callback) { //This is the second task, and callback is its callback task
        Organisation.find({}, function(err,organisations) {
            logAllThings(err,organisations);
        }); //Since we don't do anything interesting in db.save()'s callback, we might as well just pass in the task callback 
    }
], function(err) { //This is the final callback
    console.log('Both should now be printed out');
});

我遇到的问题是第二个函数（返回组织的函数）打印它们很好。然而，那个意味着返回事件的那个并不会返回{}，尽管事实上我知道这个查询是有效的，因为我已经在别处测试了它。

任何帮助将不胜感激

由于

Answer 1

你必须调用传递给每个瀑布函数的callback函数，否则它不知道它何时完成。试试这个：

async.parallel([
    function(callback) { //This is the first task, and callback is its callback task
        Event.find({}, function(err, events) {
            if (err) return callback(err);
            logAllThings(err,events);
            callback();
        });
    },
    function(callback) { //This is the second task, and callback is its callback task
        Organisation.find({}, function(err,organisations) {
            if (err) return callback(err);
            logAllThings(err,organisations);
            callback();
        }); //Since we don't do anything interesting in db.save()'s callback, we might as well just pass in the task callback 
    }
], function(err) { //This is the final callback
    console.log('Both should now be printed out');
});

Node.js Async只做一次回调

1 个答案: