Mongodb 3.2 Node js $push 不工作答案

【问题标题】：Mongodb 3.2 Node js $push is not workingMongodb 3.2 Node js $push 不工作
【发布时间】：2017-02-07 11:27:16
【问题描述】：

我想将新朋友 JSON 对象推送到数组：朋友我已经通过 mongodb 直接尝试 $push 但它不适用于 NodeJS 有谁知道wan 出了问题？

我尝试了 UsersInfo.friend -> 朋友 UsersInfo.friend.user_id -> user_id

并且没有错误返回。

播放器结构：

socket.on('follow_friend',function(data){
    var me = current_players_socket.indexOf(socket);
    console.log("PLayer id:"+data.user_id+" Player name:"+current_players[me].name+ "'s friend following request received");
    console.log("Target:"+data.fdid);
    MongoClient.connect(url,function(err,db){
        assert.equal(null,err);
        follow_friend_to_db(data,db,function(){
            db.close();
        });
    });
});

var follow_friend_to_db = function(data,db,callback){
    var me = current_players_socket.indexOf(socket);
    console.log("Following "+data.fdid+" to "+data.user_id);
            current_players[me].friend.push(data.fdid);
    db.collection('Users').update(
        {"UsersInfo.user_id":data.user_id},
        {
            $push: {
                "UsersInfo.friend" : 
                {$each:
                    {
                        "UsersInfo.friend.user_id" : data.fdid,
                        "UsersInfo.friend.add_date" : new Date("2014-10-01T00:00:00Z")
                    }
                }
            }
        },function(err,results){
            for(i= 0;i<current_players[me].friend.length;i++){
                console.log(current_players[me].friend[i]);
            }
            socket.emit('friend_followed',{fdid:data.fdid});
            callback();
        });
};

这里是 $set 函数，它是有效的

    socket.on('gold_add',function(data){
    console.log("Player id:"+data.user_id+" add gold request recevied");
    var i = current_players_socket.indexOf(socket);

    MongoClient.connect(url,function(err,db){
        assert.equal(null,err);
        update_user_gold_to_db(data,db,function(){
            db.close();
        });
    });
    console.log("Player:"+current_players[i].get_name()+"'s gold:"+current_players[i].gold);

});

var update_user_gold_to_db = function(data,db,callback){
    var i = current_players_socket.indexOf(socket);
    console.log("Player id:"+data.user_id+" add gold amount:"+data.amount);
    var t = data.amount + current_players[i].get_gold();
    console.log(t);
    db.collection('Users').update(
        {"UsersInfo.user_id":data.user_id},
        {
            $set:{"UsersInfo.gold":t}
        }, function(err,results){
            //console.log(results);
            current_players[i].gold+=data.amount;
            socket.emit('gold_add_success',{gold:current_players[i].gold});
            callback();
        });
};

【问题讨论】：

标签： javascript node.js mongodb

【解决方案1】：

为什么要使用 $each。当我们有一个数组来推送时，我们使用 $each ，就像 mongodb 文档中提到的那样：

db.inventory.update(
   { _id: 2 },
   { $addToSet: { tags: { $each: [ "camera", "electronics", "accessories" ] } } }
 )

尝试删除 $each：

var follow_friend_to_db = function(data,db,callback){
    var me = current_players_socket.indexOf(socket);
    console.log("Following "+data.fdid+" to "+data.user_id);
            current_players[me].friend.push(data.fdid);
    db.collection('Users').update(
        {"UsersInfo.user_id":data.user_id},
        {
            $push: {
                "UsersInfo.friend" : 
                    {
                        "user_id" : data.fdid,
                        "add_date" : new Date("2014-10-01T00:00:00Z")
                    }
            }
        },function(err,results){
            for(i= 0;i<current_players[me].friend.length;i++){
                console.log(current_players[me].friend[i]);
            }
            socket.emit('friend_followed',{fdid:data.fdid});
            callback();
        });
};

【讨论】：