检索MongoDB集合中对象数组中的查询元素(Retrieve the queried element in an object array in MongoDB collection)

 我有这样的MongoDB文档 
 
{
    "_id" : "toy_in_en_L02B",
    "modelCode" : "L02B",
    "path" : "/toy/in/en",
    "dataPath" : "/toy/in/en/L02B",
    "basicModelInformation" : {
        "name" : "News",
        "startingPrice" : "1234.0"
    },
    "grades" : {
        "grades" : [ 
            {
                "key" : "LVL001",
                "dataPath" : "/toy/in/en/L02B",
                "name" : "XE P",
                "price" : "1234.0"
            }, 
            {
                "key" : "LVL002",
                "dataPath" : "/toy/in/en/L02B",
                "name" : "XE P",
                "price" : "1234.0"
            },
            {
                "key" : "LVL003",
                "dataPath" : "/toy/in/en/L02B",
                "name" : "XE P",
                "price" : "1234.0"
            },
            {
                "key" : "LVL004",
                "dataPath" : "/toy/in/en/L02B",
                "name" : "XE P",
                "price" : "1234.0"
            }

        ]
    }
}
 
 现在我想检索一个只有一个等级为LVL001的完整文档。 但是当我这样查询时 
 
db.getCollection('models').find({$and: [{"dataPath" : "/nissan/in/en/L02B" }, {"grades.grades" : {$elemMatch: {"key":"LVL002"}}}]})
 
 我得到了所有成绩。 
 
 我已经检查了线程检索查询元素但没有得到它。 
 
 我的代码使用的是Spring @Query。 任何json查询参数也都很有用。 

I am having a MongoDB document like this 
 
{
    "_id" : "toy_in_en_L02B",
    "modelCode" : "L02B",
    "path" : "/toy/in/en",
    "dataPath" : "/toy/in/en/L02B",
    "basicModelInformation" : {
        "name" : "News",
        "startingPrice" : "1234.0"
    },
    "grades" : {
        "grades" : [ 
            {
                "key" : "LVL001",
                "dataPath" : "/toy/in/en/L02B",
                "name" : "XE P",
                "price" : "1234.0"
            }, 
            {
                "key" : "LVL002",
                "dataPath" : "/toy/in/en/L02B",
                "name" : "XE P",
                "price" : "1234.0"
            },
            {
                "key" : "LVL003",
                "dataPath" : "/toy/in/en/L02B",
                "name" : "XE P",
                "price" : "1234.0"
            },
            {
                "key" : "LVL004",
                "dataPath" : "/toy/in/en/L02B",
                "name" : "XE P",
                "price" : "1234.0"
            }

        ]
    }
}
 
Now I want to retrieve a complete Document with having only one grade as LVL001. But when I am querying this like 
 
db.getCollection('models').find({$and: [{"dataPath" : "/nissan/in/en/L02B" }, {"grades.grades" : {$elemMatch: {"key":"LVL002"}}}]})
 
I am getting all the grades.
 
I already checked the thread Retrieve Queried Element but not getting it.
 
My code is using the Spring @Query. Any json query parameter for this will also be useful.

原文：https://stackoverflow.com/questions/44656666