Mongodb 按Id获取文档时,使用$addFields动态填充字段
在MongoDB集合中运行getById()函数时,我想使用Mongodb 按Id获取文档时,使用$addFields动态填充字段,mongodb,mongoose,aggregation-framework,Mongodb,Mongoose,Aggregation Framework,在MongoDB集合中运行getById()函数时,我想使用$aggregate和$addFields动态填充字段。基本上,我想做的是从一个名为“history”的属性中提取对象数组中的最后一个元素,并将其动态填充到一个名为“activeStatus”的字段中,该字段是一个对象。这段特殊的代码如下所示: await db.collection("staffmembers").aggregate([{ $addFields: { activeStatus: { $arrayElemAt: ["$h
$aggregate
和$addFields
动态填充字段。基本上,我想做的是从一个名为“history”的属性中提取对象数组中的最后一个元素,并将其动态填充到一个名为“activeStatus”的字段中,该字段是一个对象。这段特殊的代码如下所示:
await db.collection("staffmembers").aggregate([{ $addFields: { activeStatus: { $arrayElemAt: ["$history", -1.0] } } }, { $out: "staffmembers" }]);
{
"_id": <id value>,
"type": "permanent",
"gender": "female",
"history": [
{
"endDate": "2018-10-31T12:27:17.721Z",
"stage": "training",
"completed": true,
"startDate": "2018-10-30T13:41:18.714Z"
},
{
"stage": "active",
"completed": false,
"startDate": "2018-10-31T12:27:17.572Z"
}
]
}
完整的getById()函数如下所示:
exports.getById = async function(req, res) {
let doc;
let MongoClient = await require("../config/database")();
let db = MongoClient.connection.db;
let request = new EndpointRequestController(
req,
res,
// Allowed Parameters
{
id: {
type: String
}
},
[
// Required Parameters
"id"
]
);
await db.collection("staffmembers").aggregate([{ $addFields: { activeStatus: { $arrayElemAt: ["$history", -1.0] } } }, { $out: "staffmembers" }]);
try {
doc = await StaffMember.findOne(
{
_id: request.parameters.id
},
{}
).exec();
if (doc) req.documentCount = 1;
} catch (err) {
return request.sendError("An error occurred while trying to find existing records.", err);
}
res.send(doc);
};
虽然我没有收到任何错误,但在生成的文档中看不到“activeStatus”
在这种情况下我能做些什么吗?如果是这样,我错过了什么
顺便说一下,我的文档如下所示:
await db.collection("staffmembers").aggregate([{ $addFields: { activeStatus: { $arrayElemAt: ["$history", -1.0] } } }, { $out: "staffmembers" }]);
{
"_id": <id value>,
"type": "permanent",
"gender": "female",
"history": [
{
"endDate": "2018-10-31T12:27:17.721Z",
"stage": "training",
"completed": true,
"startDate": "2018-10-30T13:41:18.714Z"
},
{
"stage": "active",
"completed": false,
"startDate": "2018-10-31T12:27:17.572Z"
}
]
}
{
“_id”:,
“类型”:“永久”,
“性别”:“女性”,
“历史”:[
{
“结束日期”:“2018-10-31T12:27:17.721Z”,
“阶段”:“培训”,
“完成”:正确,
“起始日期”:“2018-10-30T13:41:18.714Z”
},
{
“阶段”:“活动”,
“已完成”:错误,
“开始日期”:“2018-10-31T12:27:17.572Z”
}
]
}
这是我想制作的文件:
{
"_id": <id value>,
"type": "permanent",
"gender": "female",
"history": [
{
"endDate": "2018-10-31T12:27:17.721Z",
"stage": "training",
"completed": true,
"startDate": "2018-10-30T13:41:18.714Z"
},
{
"stage": "employed",
"completed": false,
"startDate": "2018-10-31T12:27:17.572Z"
}
],
"activeStatus": {
"stage": "employed",
"completed": false,
"startDate": "2018-10-31T12:27:17.572Z"
}
}
{
“_id”:,
“类型”:“永久”,
“性别”:“女性”,
“历史”:[
{
“结束日期”:“2018-10-31T12:27:17.721Z”,
“阶段”:“培训”,
“完成”:正确,
“起始日期”:“2018-10-30T13:41:18.714Z”
},
{
“阶段”:“雇佣”,
“已完成”:错误,
“开始日期”:“2018-10-31T12:27:17.572Z”
}
],
“活动状态”:{
“阶段”:“雇佣”,
“已完成”:错误,
“开始日期”:“2018-10-31T12:27:17.572Z”
}
}
此行:
wait db.collection(“staffmembers”).aggregate([{$addFields:{activeStatus:{$arrayElemAt:[“$history”,-1.0]}}},{$out:“staffmembers”}])
返回类型,因为您正在使用raw node.js MongoDB驱动程序。所以实际上没有执行数据库调用
有两种方法可以解决此问题:
1) 使用mongoose API:
await StaffMember.aggregate([{ $addFields: { activeStatus: { $arrayElemAt: ["$history", -1.0] } } }, { $out: "staffmembers" }]);
2) “强制”光标执行查询(使用next()
或toArray()
)
我猜aggregate前面缺少await,你能试试吗?我在aggregate块前面添加了“await”,但仍然不行。