Question

我正在使用mongodb做项目。所以在这里我只需要检索文档元素的数组搜索文档的选定字段。这是我的榜样。

{
        "_id": {
            "$id": "515ce66ca00b2aa30a000000"
        },
        "user_id": "user_1111",
        "events": [
            {
                "subject": "it test I",
                "start_date": "04/14/2013",
                "start_time": "8.00 AM",
                "end_date": "04/14/2013",
                "end_time": "10.30 AM",
                "all_day_event": "false",
                "discription": "no discription",
                "location": "STC",
                "private": "false",
                "time_zone": "IST",
                "alarm": "true",
                "alarm_threshold": "5",
                "status": "true"
            }
        ]
    }

所以我需要检索以下结果。

           {
                "subject": "it test I",
                "start_date": "04/14/2013",
                "start_time": "8.00 AM",
                "end_date": "04/14/2013",
                "end_time": "10.30 AM",
                "all_day_event": "false",
                "discription": "no discription",
                "location": "STC",
                "private": "false",
                "time_zone": "IST",
                "alarm": "true",
                "alarm_threshold": "5",
                "status": "true"
            }

搜索

{“events.subject”：“它测试我”} 我是怎么做到的请帮帮我。

Answer 1

我不确定是否有一种直接的方式来做你想做的事情，但你可以尝试以下方法：

如果文档中的事件不超过1 ，您只需进行投影：

db.events.find({"events.subject":"it test I"},{events:1,_id:0}).pretty()
{
    "events" : [
        {
            "subject" : "it test I",
            "start_date" : "04/14/2013",
            "start_time" : "8.00 AM",
            "end_date" : "04/14/2013",
            "end_time" : "10.30 AM",
            "all_day_event" : "false",
            "discription" : "no discription",
            "location" : "STC",
            "private" : "false",
            "time_zone" : "IST",
            "alarm" : "true",
            "alarm_threshold" : "5",
            "status" : "true"
        }
    ]
}

但是，您仍会以键值格式获得结果。如果您使用的是驱动程序，也许可以轻松检索该值。

如果文档中的事件可能超过1 ，我担心您只能使用$elemMatch为每个匹配的文档获取第一个匹配的子文档：
```
db.events.find({"events.subject":"it test I"},{events:{$elemMatch:{"subject":"it test I"}},_id:0}).pretty()
```
你得到的结果与no相同。 1。

您可以尝试使用聚合框架来检索所有匹配的文档：

db.events.aggregate(
{$match: {"events.subject":"it test I"}},
{$unwind: "$events"},
{$match: {"events.subject":"it test I"}},
{
  $project:{
    _id: 0,
    subject: "$events.subject",
    start_date: "$events.start_date",
    end_date: "$events.end_date",
    end_time: "$events.end_time",
    all_day_event: "$events.all_day_event",
    discription: "$events.discription",
    location: "$events.location",
    private: "$events.private",
    time_zone: "$events.time_zone",
    alarm: "$events.alarm",
    alarm_threshold: "$events.alarm_threshold",
    status: "$events.status"
  }
})
{
    "result" : [
        {
            "subject" : "it test I",
            "start_date" : "04/14/2013",
            "end_date" : "04/14/2013",
            "end_time" : "10.30 AM",
            "all_day_event" : "false",
            "discription" : "no discription",
            "location" : "STC",
            "private" : "false",
            "time_zone" : "IST",
            "alarm" : "true",
            "alarm_threshold" : "5",
            "status" : "true"
        }
    ],
    "ok" : 1
}

使用mongodb如何在Document of Document字段中检索部分文档搜索

1 个答案: