Question

如何从以下BSON文档中获取子文档值

{
"_id" : ObjectId("52415e45ccf279207b91a2a0"),
"created" : ISODate("2013-09-24T09:41:25.760Z"),
"creator" : "52415e45ccf279207b91a29e",
"description" : "Lorem ipsum dolor sit amet, consectetur adipiscing elit.",
"lastModif" : ISODate("2013-09-24T09:41:25.760Z"),
"title" : "My post title",
"comments" : [ 
    {
        "title" : "Comment 1",
        "content" : "Lorem ipsum dolor sit amet, consectetur adipiscing elit.",
        "created" : ISODate("2013-09-24T09:41:25.764Z"),
        "lastModif" : ISODate("2013-09-24T09:41:25.764Z"),
        "creator" : "52415e45ccf279207b91a2a3",
        "_id" : ObjectId("52415e45ccf279207b91a2a1")
    },
    {
        "title" : "Comment 2",
        "content" : "Lorem ipsum dolor sit amet, consectetur adipiscing elit.",
        "created" : ISODate("2013-09-24T09:41:25.764Z"),
        "lastModif" : ISODate("2013-09-24T09:41:25.764Z"),
        "creator" : "52415e45ccf279207b91a2a3",
        "_id" : ObjectId("52415e45ccf279207b91a29f")
    },
    {
        "title" : "Comment 3",
        "content" : "Lorem ipsum dolor sit amet, consectetur adipiscing elit.",
        "created" : ISODate("2013-09-24T09:41:25.764Z"),
        "lastModif" : ISODate("2013-09-24T09:41:25.764Z"),
        "creator" : "52415e45ccf279207b91a2a3",
        "_id" : ObjectId("52415e45ccf279207b91a287")
    }
... 
  ]
}

我需要获取title='Comment 1'。

的子文档

任何人都可以帮助我。

Answer 1

如果您想查找包含 title =“Comment 1”的评论的文档，那么您可以使用：

db.test.find({"comments.title" : "Comment 1"})

如果您还希望投影结果以便它只显示子文档，那么您应该按如下方式更新查询：

db.test.find({"comments.title" : "Comment 1"},{comments : {$elemMatch : {title:"Comment 1"}}})

如何从以下BSON文档中获取子文档值

1 个答案: