5
我正在處理消息系統,我需要從發送消息給登錄用戶的每個用戶獲取最後一條消息。我在MongoDB的這種結構:貓鼬 - 找到每個用戶的最後一條消息
[{
"_id": "551bd621bb5895e4109bc3ce",
"from": "admin",
"to": "user1",
"message": "message1",
"created": "2015-04-01T11:27:29.671Z"
}, {
"_id": "551bd9acf26208ac1d9b831d",
"from": "user1",
"to": "admin",
"message": "message2",
"created": "2015-04-01T11:42:36.936Z"
}, {
"_id": "551bdd6d849d53001dd8a64a",
"from": "user1",
"to": "user2",
"message": "message3",
"created": "2015-04-01T11:58:37.858Z"
}, {
"_id": "551bdd99849d53001dd8a64b",
"from": "user2",
"to": "admin",
"__v": 0,
"message": "message4",
"created": "2015-04-01T11:59:21.005Z"
}, {
"_id": "551bdda1849d53001dd8a64c",
"from": "user1",
"to": "admin",
"__v": 0,
"message": "message5",
"created": "2015-04-01T11:59:29.971Z"
}]
我需要從誰發送消息給用戶登錄每個用戶的最後消息得到場from
,message
和created
。我嘗試使用不同,但它只返回一個字段。我有這樣的:
Message.find({
to: req.user.username
})
.select('message created')
.sort('-created')
.exec(function (err, messages) {
if (err) {
return res.status(400).send({
message: getErrorMessage(err)
});
} else {
res.json(messages)
}
});
但它返回誰發信息登錄的用戶的所有用戶,我需要有獨特的只有用戶和他們的最後一條消息。有什麼方法如何用貓鼬做到這一點?
的可能重複[ Mongodb查詢:每個項目的日期最新記錄](http://stackoverflow.com/questions/29368141/mongodb-query-latest-record-by-date-for-each-item) – Dineshaws 2015-04-02 10:34:28