mongodb - 如何在 mongoDB 中使用通配符字段？

Question

谁能帮我提取包含“澳大利亚”作为国家/地区的记录，而我们不知道 Mongo 查询中日期映射中的键(日期)。

我的样本数据....

`{
    "_id" : ObjectId("5bfbdf1f123ee9f1b2bb82e0"),
    "fruit" : "apple",
    "datemap" : {
        "11/26/2018" : [ 
            {
                "_id" : "bbc2bb53-b7fe-43ec-9e88-38efbd69c345",
                "country" : "Denmark"
            }
        ],
            "11/27/2018" : [ 
            {
                "_id" : "bbc2bb53-b7fe-43ec-9e88-38efbd68c345",
                "country" : "Norway"
            }
        ],
            "11/28/2018" : [ 
            {
                "_id" : "bbc2bb54-b7fe-43ec-9e88-38efbd68c345",
                "country" : "Australia"
            }
        ]
    }
},
{
    "_id" : ObjectId("5bfbdf1f123ee9f1b2bb8245"),
    "fruit" : "Orange",
    "datemap" : {
        "11/26/2018" : [ 
            {
                "_id" : "bbc2bb53-b7fe-43ec-9e88-38efbd69c345",
                "country" : "Brazil"
            }
        ],
            "11/29/2018" : [ 
            {
                "_id" : "bbc2bb53-b7fe-43ec-9e88-38efbd68c345",
                "country" : "England"
            }
        ],
            "11/30/2018" : [ 
            {
                "_id" : "bbc2bb54-b7fe-43ec-9e88-38efbd68c345",
                "country" : "Australia"
            }
        ]
    }
}`

提前致谢....

Answer 1

您可以使用 $objectToArray将未知 key 转换为 k v 对，然后放入 $match健康)状况。

有点像

db.collection.aggregate([
  { "$addFields": { "country": { "$objectToArray": "$datemap" } } },
  { "$match": { "country.v.country": "Australia" } },
  { "$project": { "country": 0 }}
])