如何在mongoDb文档中查找特定的数组元素，并使用范围进行查询和筛选？

我有一个以以下格式存储文档的集合：

/* 1 */
{
    "_id" : ObjectId("5cc1a108c5475b9e91bb7830"),
    "item" : "journal",
    "instock" : [ 
        {
            "warehouse" : "A",
            "qty" : 5.0
        }, 
        {
            "warehouse" : "C",
            "qty" : 15.0
        }
    ]
}

/* 2 */
{
    "_id" : ObjectId("5cc1a108c5475b9e91bb7831"),
    "item" : "notebook",
    "instock" : [ 
        {
            "warehouse" : "C",
            "qty" : 5.0
        }
    ]
}

/* 3 */
{
    "_id" : ObjectId("5cc1a108c5475b9e91bb7832"),
    "item" : "paper",
    "instock" : [ 
        {
            "warehouse" : "A",
            "qty" : 60.0
        }, 
        {
            "warehouse" : "B",
            "qty" : 15.0
        }
    ]
}

/* 4 */
{
    "_id" : ObjectId("5cc1a108c5475b9e91bb7833"),
    "item" : "planner",
    "instock" : [ 
        {
            "warehouse" : "A",
            "qty" : 40.0
        }, 
        {
            "warehouse" : "B",
            "qty" : 5.0
        }
    ]
}

/* 5 */
{
    "_id" : ObjectId("5cc1a108c5475b9e91bb7834"),
    "item" : "postcard",
    "instock" : [ 
        {
            "warehouse" : "B",
            "qty" : 15.0
        }, 
        {
            "warehouse" : "C",
            "qty" : 35.0
        },
        {
            "warehouse" : "M",
            "qty" : 50.0
        }
    ]
}

/* 6 */
{
    "_id" : ObjectId("5cc1a16ea794ebd5fc278172"),
    "item" : "dig",
    "instock" : [ 
        {
            "warehouse" : "A",
            "qty" : 5.0
        }
    ]
}

我想找到数量大于指定值且小于其他指定值的特定单据数组

例如，我希望项目“明信片”和instock值大于10且小于40，因此它返回明信片的文档，其中instock数组仅包含一个匹配的元素，就像输出一样：

/* 1 */
    {
        "_id" : ObjectId("5cc1a108c5475b9e91bb7834"),
        "item" : "postcard",
        "instock" : [ 
            {
                "warehouse" : "B",
                "qty" : 15.0
            }, 
            {
                "warehouse" : "C",
                "qty" : 35.0
            }
        ]
    }

可用于文档级筛选，并将条件应用于数组：

db.collection.aggregate([
    {
        $match: { item: "postcard" }
    },
    {
        $addFields: {
            instock: {
                $filter: {
                    input: "$instock",
                    cond: {
                        $and: [
                            { $gt: [ "$$this.qty", 10 ] },
                            { $lt: [ "$$this.qty", 30 ] }
                        ]
                    }
                }
            }
        }
    }
])

---

我认为您提到的输出不正确，根据您的问题，它应该只返回“仓库”的一个元素：“B”是的，以前输出不正确，但我现在编辑了我的问题。