MongoDB从嵌套文档中检索选定对象

是否可以在嵌套文档中查询特定对象？举个例子

Collection : Threads
{
    Documents : Messages
    {
        threadId = 1
        messages = [
            {
                user = amy
                date = 01/01/2012
                content = hey
            },
            {
                user = bell
                date = 01/01/2012
                content = hey
            },
            {
                user = bell
                date = 01/02/2012
                content = whats up
            }
        ]
    },
    {
        threadId = 2
        messages = [
            {
                user = courtney
                date = 01/03/2012
                content = first!
            }
        ]
    }
}

我希望我的查询是

{threadId:1，'messages.date'：{$gt:01/01/2012}，{fields:{messages:1}}

。但它会返回所有文档消息，而我真正想要的结果是

messages = [
    {
        user = bell
        date = 01/02/2012
        content = whats up
    }
]

---

。你会得到所有的。因此，您必须在客户端进行筛选

使用MongoDB聚合管道可以为您提供一个解决方案！