nodeJS 创建动态数组并用作响应答案

【问题标题】：nodeJS create dynamic array and use as responsenodeJS 创建动态数组并用作响应
【发布时间】：2015-12-06 12:39:11
【问题描述】：

您好，我正在创建一个空数组，然后使用 forEach 循环使用来自 mongo 查询的数据填充它。

我现在已经尝试了 4 天，但我似乎没有做任何工作，我知道我很接近，但作为 javascript 和 MEAN 堆栈的新手，我只是想不通。

我在我想做的所有事情上都附上了带有 cmets 的代码。

任何帮助都会很棒..

var mongoose = require('mongoose'),
    User = require('../../models/UserModel'),
    async = require('async');


module.exports.getfollowing = function(req, res){

    //grab the Users ID from the body
    var thefollower = req.body.follower;

    //create empty array that i want to populate with the followee's ID and Avatar url
    var obj = [];

    //query mongo for the user
    User.findOne({ _id: thefollower }, function (err, user) {

            if (err) {

                console.log(err);
                res.json(err); 

            } else {

                //grab the following element of the users mongo schema -- should return all the followee's ID's -- tested works
                var following = user.following;

                //iritate throught all the followee's
                async.forEach(following, function(item, callback) {

                    //current followee
                    var user = item;

                    //query mongo for the followee
                    User.findOne({_id: user}, function(err, followee, callback){

                        //get followee's ID and Avatar url
                        var id = followee._id;
                        var avatar = followee.avatar;


                       //add the followee's ID and Avatar url to the obj array 
                       obj.push({                
                            id: id,
                            avatar: avatar                 
                       });

                    }); 

                    //see if this worked - returns empty
                    console.log(obj);
                    callback();

                }, function(err) {

                    //see if this worked - returns empty
                    console.log(obj);

                    //respond to the client - returns empty
                    res.json(obj);  

                });                  
            }   
    });  
};

【问题讨论】：

标签： javascript arrays node.js mongodb express

【解决方案1】：

您需要将位于async.forEach() 回调末尾的callback(); 移动到User.findOne({_id: user}, ...) 回调内部（在您调用obj.push() 之后），因为那是您真正完成item 的时间.使用您当前的代码，在您的 mongo 查询有机会完成之前，您会立即告诉 async 模块您已完成 item。

【讨论】：

【解决方案2】：

mscdex

发现他的回答解决了我的问题，以便将来帮助其他人，这里是代码

var mongoose = require('mongoose'),
    User = require('../../models/UserModel'),
    async = require('async');


module.exports.getfollowing = function(req, res){

    //grab the Users ID from the body
    var thefollower = req.body.follower;

    //create empty array that i want to populate with the followee's ID and Avatar url
    var obj = [];

    //query mongo for the user
    User.findOne({ _id: thefollower }, function (err, user) {

            if (err) {

                console.log(err);
                res.json(err); 

            } else {

                //grab the following element of the users mongo schema -- should return all the followee's ID's -- tested works
                var following = user.following;

                //iritate throught all the followee's
                async.forEach(following, function(item, callback) {

                    //current followee
                    var user = item;

                    //query mongo for the followee
                    User.findOne({_id: user}, function(err, followee){

                        //get followee's ID and Avatar url
                        var id = followee._id;
                        var avatar = followee.avatar;


                       //add the followee's ID and Avatar url to the obj array 
                       obj.push({                
                            id: id,
                            avatar: avatar                 
                       });

                    //see if this worked - returns empty
                    console.log(obj);
                    callback();

                    }); 


                }, function(err) {

                    //see if this worked - returns empty
                    console.log(obj);

                    //respond to the client - returns empty
                    res.json(obj);  

                });                  
            }   
    });  
};

【讨论】：