mongodb - 在 MongoDB 中形成具有聚合的数组
问题描述
我在 MongoDB 3.4 中有一个具有以下结构的文档:
{
"_id" : ObjectId("5e3419e468d01013eadb83dc"),
"id_station" : "62",
"fiware_service" : null,
"fiware_servicepath" : null,
"id_fiware_name" : "CE_del_medio",
"attrName" : "15",
"attrType" : "float",
"attrValue" : 0.33,
"id_sensor_station_absolute" : "15_62",
"recvTimeTs" : 1580387045,
"recvTime" : "2020-01-30T12:24:05.00Z",
"id_fiware" : "15",
"sensor_type" : [
{
"name" : "id",
"type" : "String",
"value" : "15"
},
{
"name" : "img",
"type" : "String",
"value" : "assets/img/contrast.png"
},
{
"name" : "manufacturer",
"type" : "String",
"value" : "Hortisis"
},
{
"name" : "medida",
"type" : "String",
"value" : "mS/cm"
},
{
"name" : "name_comun",
"type" : "String",
"value" : "CE del medio"
},
{
"name" : "place",
"type" : "String",
"value" : "interior"
},
{
"name" : "timestamp",
"type" : "DateTime",
"value" : "2020-01-30T12:24:05.00Z"
},
{
"name" : "type",
"type" : "String",
"value" : "fertigation"
}
]
}
我需要将 sensor_type 字段转换为只有一个对象的数组,如下所示:
{
"_id":"15_62",
"medidas":[
{
"_id":"5e3419e468d01013eadb83dc",
"marca":"Hortisis",
"modelo":"Estacion",
"fabricante":"Hortisis",
"id_station":"15",
"sensor_type":[
{
"name":"15",
"type":"fertigation",
"place":"interior",
"img":"assets/img/contrast.png",
"name_comun":"Temp. Suelo",
"medida":"mS/cm"
}
],
"attrName":"15",
"attrValue":0.33,
"recvTimeTs":1580387045,
"recvTime":"2020-01-30T12:24:05.00Z",
"id_sensor_station_absolute":"15_62"
}
]
}
如您所见,它正在格式化 sensor_type 字段 = 名称:值。
我正在使用 NODEJS 和猫鼬。
这是我的查询:(首先我搜索,排序,只显示第一个值,然后使用我给出格式的项目,问题是如果我输入“sensor_type”,我不知道如何告诉项目输入该格式: "$latest.attributes.name") 它只显示名称,我不知道如何以上述格式显示。
Datagreenhouse.aggregate([
{ "$match": { "id_sensor_station_absolute": { "$in": array3 } } }, // "id_station": { "$in": id_station },
{ "$sort": { "recvTime": -1 } },
{
"$group": {
"_id": "$id_sensor_station_absolute",
"latest": { "$first": "$$ROOT" },
}
},
{
"$project": {
"_id": 1,
"id_station": "$latest.id_station",
//"id_sensor_station_absolute": "$id_sensor_station_absolute",
"attrName": "$latest.attrName",
"attrValue": "$latest.attrValue",
"recvTimeTs": "$latest.recvTimeTs",
"recvTime": "$latest.recvTime",
"id_sensor_station_absolute": "$latest.id_sensor_station_absolute",
"sensor_type": "$latest.attributes",
"name": { $arrayElemAt: ["$latest.attributes", 0] },
"type": { $arrayElemAt: ["$latest.attributes", 1] },
"place": { $arrayElemAt: ["$latest.attributes", 2] },
"img": { $arrayElemAt: ["$latest.attributes", 1] },
"name_comun": { $arrayElemAt: ["$latest.attributes", 4] },
"medida": { $arrayElemAt: ["$latest.attributes", 3] },
"interfaz": { $arrayElemAt: ["$latest.attributes", 6] },
}
}
], (err, DatagreenhouseRecuperado) => {
if (err) return res.status(500).send({ message: 'Error al realizar la peticion' + err })
if (!DatagreenhouseRecuperado) return res.status(404).send({ message: 'Error el usuario no existe' })
res.status(200).send({ DatagreenhouseRecuperado })
})
谢谢您的帮助。此致。
解决方案
从 3.4.4 版本开始,MongoDB 引入了一个 magnific 运算符:$arrayToObject
该运算符允许我们将数组key:value
对转换为对象。
句法
RAW DATA $map $arrayToObject
sensor_type : [ sensor_type : [ sensor_type : {
{ \ { \
"name" : "manufacturer", ----> k: "manufacturer", --->
"type" : "String", / v: "Hortisis" / "manufacturer" : "Hortisis"
"value" : "Hortisis"
} }
] ] }
db.datagreenhouses.aggregate([
{
"$match": {} // setup your match criteria
},
{
"$sort": {
"recvTime": -1
}
},
{
$group: {
_id: "$id_sensor_station_absolute",
medidas: {
$push: {
_id: "$_id",
"marca": "Hortisis", // don't know where you get this value
"modelo": "Estacion", // don't know where you get this value
"id_station": "$id_station",
"attrName": "$attrName",
"attrValue": "$attrValue",
"recvTimeTs": "$recvTimeTs",
"recvTime": "$recvTime",
"id_sensor_station_absolute": "$id_sensor_station_absolute",
"sensor_type": {
$arrayToObject: {
$map: {
input: "$sensor_type",
in: {
k: "$$this.name",
v: "$$this.value"
}
}
}
}
}
}
}
}
])
[
{
"_id": "15_62",
"medidas": [
{
"_id": ObjectId("5e3419e468d01013eadb83dc"),
"attrName": "15",
"attrValue": 0.33,
"id_sensor_station_absolute": "15_62",
"id_station": "62",
"marca": "Hortisis",
"modelo": "Estacion",
"recvTime": "2020-01-30T12:24:05.00Z",
"recvTimeTs": 1.580387045e+09,
"sensor_type": {
"id": "15",
"img": "assets/img/contrast.png",
"manufacturer": "Hortisis",
"medida": "mS/cm",
"name_comun": "CE del medio",
"place": "interior",
"timestamp": "2020-01-30T12:24:05.00Z",
"type": "fertigation"
}
}
]
}
]
您需要做的就是使用易于处理的对象($unwind
medidas 字段,转换然后$group
再次)将数据转换为所需的结果
注意:如果您的 MongoDB 是 3.4.4 之前的版本,请按照更新程序进行操作:
- 安装 MongoDB 3.4.4 或更新版本
mongodump
使用新版本 MongoBD制作- 停止旧的 MongoBD
- 删除 /data 目录(进行备份)
- 启动新的 MongoDB 并运行
mongorestore
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