如何获取mongoose中文档数组中匹配条件的对象总数

Question

我有数据需要获取设备为工作分配的批次数。我的数据样本具有以下格式

    "_id" : ObjectId("5968c6aa5a44c946bc13d184"), 
    "listType" : "OPEN", 
"resourceAssigned" : [
    {
        "deviceId" : "59522e01e67d9f1adcd7a158", 
        "capacity" : "2", 
        "lot" : NumberInt(1)
    }, 
    {
        "deviceId" : "59522e01e67d9f1adcd7a158", 
        "capacity" : "7", 
        "lot" : NumberInt(2)
    }, 
    {
        "deviceId" : "59522e01e67d9f1adcd7a158", 
        "capacity" : "5", 
        "lot" : NumberInt(3)
    },
            {
        "deviceId" : "59522e01e67d9f1adcd7a151", 
        "capacity" : "6", 
        "lot" : NumberInt(1)
    }, 
    {
        "deviceId" : "59522e01e67d9f1adcd7a151", 
        "capacity" : "3", 
        "lot" : NumberInt(2)
    }
], 
"materialHandlingUnit" : [

], 
"__v" : NumberInt(0)

如果我需要搜索ang得到针对deviceId键的计数，那么它应该返回它在resourceAssigned数组中的次数。什么查询可以帮助我解决这个问题？

从我这边建立查询的试验是：

            var pickListId = req.body.pickListId;
        var deviceId = req.body.deviceId;

        var pipeline = [
            {"$match": {"resourceAssigned.deviceId": deviceId}},
            {"$unwind": "$resourceAssigned"},
            {"$match": {"resourceAssigned.deviceId": deviceId}},
            {
                "$group": {
                    "_id": '$_id',
                    "numberOfEntries": {"$sum": 1}
                }
            }
        ];

        pickListModel.aggregate(pipeline, function (err, pickAggregateRecord) {

            if (err) {

                res.json({message: 'INTERNAL SERVER ERROR, UNKNOWN SERVER ERROR HAS OCCURRED!!!!!', status: 'error', statusCode: '500'});
            } else {

                res.json(pickAggregateRecord);
            }
        });

上述查询有效，但没有针对指定的＆＃39; _id＆＃39;进行查找的条件。我想要的查询应该作为findOne工作而不能找到。