小编Đức*_*yễn的帖子

我有一个包含以下文件的产品系列:

{ "_id" : 1, "item" : "abc", created: ISODate("2014-10-01T08:12:00Z") }
{ "_id" : 2, "item" : "jkl", created: ISODate("2014-10-02T09:13:00Z") }
{ "_id" : 3, "item" : "hjk", created: ISODate("2014-10-02T09:18:00Z") }
{ "_id" : 4, "item" : "sdf", created: ISODate("2014-10-07T09:14:00Z") }
{ "_id" : 5, "item" : "xyz", created: ISODate("2014-10-15T09:15:00Z") }
{ "_id" : 6, "item" : "iop", created: ISODate("2014-10-16T09:15:00Z") }

我想绘制一个描述产品数量的图表,所以我使用mongodb聚合框架按天计算产品组:

  var proj1 = {
      "$project": {
          "created": 1,
          "_id": 0,
          "h": {"$hour": "$created"},
          "m": {"$minute": "$created"},
          "s": {"$second": …

我在将mongodb数据放入nodejs数组时遇到问题，如下所示：

测试数据库：

{
  "supportTicket" : "viT8B4KsRI7cJF2P2TS7Pd0mfqaI5rtwf",
  "msgId" : 1379304604708.0,
  "username" : "Guest-OSsL2R",
  "message" : "hello",
  "_id" : ObjectId("5236849c3651b78416000001")
}

Nodejs：

function _getMsg(st, callback) {
    db.test.find({ supportTicket: st }).toArray(function (err, docs) {
        callback(docs);
    });
}

var nodeArr = _getMsg('viT8B4KsRI7cJF2P2TS7Pd0mfqaI5rtwf', function (res) {
    console.log(res); // --> res contain data and printed ok
    return res; 
});

console.log('return data: ' + nodeArr )  // --> However, nodeArr  is undefined.

结果如下：

return data: undefined
return data: undefined
[ { supportTicket: 'viT8B4KsRI7cJF2P2TS7Pd0mfqaI5rtwf',
    msgId: 1379304604708,
    username: 'Guest-OSsL2R', …