查询子文档并从中选择过滤后的数据 Mongoose
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【中文标题】查询子文档并从中选择过滤后的数据 Mongoose【英文标题】：Query a subdocument and select filtered data from it Mongoose 【发布时间】：2021-10-23 06:07:33 【问题描述】：我想查询位于父文档中的子文档，并且只选择（在快速响应中返回）具有自己数据的特定子文档，但我这样做的方式是选择/返回所有子文档，没有过滤我需要的，我试图通过字段candidateId进行过滤
这是我的查询：
interviewRouter.get(
"/:idCandidato&:userEmail",
async (req: Request, res: Response) =>
const idCandidato, userEmail = req.params;
parseInt(idCandidato);
const infoCandidato = await User.find(
email: userEmail,
"candidates.candidateId": idCandidato,
).select("_id": 0, "candidates": 1);
infoCandidato
? res.status(200).json( Candidato: infoCandidato )
: res.status(404).json( Candidato: "Candidato no encontrado" );
);
这是我的文档和子文档结构：
"_id" : ObjectId("61223b3c88e21fe0ee69d689"),
"username" : "randomUserName",
"email" : "random@email.com",
"pictureUrl" : "some/url/to/the/user/picture/username",
"role" : "admin",
"candidates" : [
"_id" : ObjectId("612242cd11a7f1ebc6a18661"),
"candidateName" : "some candidates name",
"candidateId" : 123,
"candidateInfo" : [
"_id" : ObjectId("612242cd11a7f1ebc6a18662"),
"currentSituation" : "3",
"motivationToChange" : "3",
"postSavingDate" : ISODate("2021-08-22T12:27:57.490Z")
,
"_id" : ObjectId("612242cd11a7f1ebc6a04854"),
"currentSituation" : "6",
"motivationToChange" : "7",
"postSavingDate" : ISODate("2021-08-22T13:56:57.490Z")
],
"availableNow" : false,
"mainSkills" : "MM"
,
"_id" : ObjectId("612261abf7b68bfaf56345df"),
"candidateName" : "some other guy",
"candidateId" : 1234,
"candidateInfo" : [
"_id" : ObjectId("612261abf7b68bfaf56345e0"),
"currentSituation" : "dunno",
"motivationToChange" : "no idea",
"postSavingDate" : ISODate("2021-08-22T14:39:39.161Z")
],
"availableNow" : false,
"mainSkills" : "javascript"
],
"__v" : 0
在下面，您可以看到我的查询返回的内容，基本上是整个 candidates 集合，而不是我需要的过滤后的子文档：
"Candidato": [
"candidates": [
"_id" : ObjectId("612242cd11a7f1ebc6a18661"),
"candidateName" : "some candidates name",
"candidateId" : 123,
"candidateInfo" : [
"_id" : ObjectId("612242cd11a7f1ebc6a18662"),
"currentSituation" : "3",
"motivationToChange" : "3",
"postSavingDate" : ISODate("2021-08-22T12:27:57.490Z")
,
"_id" : ObjectId("612242cd11a7f1ebc6a04854"),
"currentSituation" : "6",
"motivationToChange" : "7",
"postSavingDate" : ISODate("2021-08-22T13:56:57.490Z")
],
"availableNow" : false,
"mainSkills" : "MM"
,
"_id" : ObjectId("612261abf7b68bfaf56345df"),
"candidateName" : "some other guy",
"candidateId" : 1234,
"candidateInfo" : [
"_id" : ObjectId("612261abf7b68bfaf56345e0"),
"currentSituation" : "dunno",
"motivationToChange" : "no idea",
"postSavingDate" : ISODate("2021-08-22T14:39:39.161Z")
],
"availableNow" : false,
"mainSkills" : "JavaScript"
]
]
重要提示：请记住，我只希望它返回123 或1234 子文档，具体取决于我传递给查询的candidateId
这是我找到的解决方法，但我认为有点脏，希望有另一种选择：
interviewRouter.get(
"/:idCandidato&:userEmail",
async (req: Request, res: Response) =>
const idCandidato, userEmail = req.params;
const infoCandidato = await User.findOne(
email: userEmail,
"candidates.candidateId": idCandidato,
,
function (err: any, response: any)
if (err)
res.status(400).send(err);
else
let newResponse = response["candidates"].filter((element: any) =>
return element.candidateId === parseInt(idCandidato);
);
res.status(200).json( Candidato: newResponse );
);
通过这种解决方法，我得到了我需要的东西，但它看起来有点乱，我觉得可能还有其他更清洁的解决方案。这是我得到的回报：
"Candidato": [
"_id" : ObjectId("612242cd11a7f1ebc6a18661"),
"candidateName" : "some candidates name",
"candidateId" : 123,
"candidateInfo" : [
"_id" : ObjectId("612242cd11a7f1ebc6a18662"),
"currentSituation" : "3",
"motivationToChange" : "3",
"postSavingDate" : ISODate("2021-08-22T12:27:57.490Z")
,
"_id" : ObjectId("612242cd11a7f1ebc6a04854"),
"currentSituation" : "6",
"motivationToChange" : "7",
"postSavingDate" : ISODate("2021-08-22T13:56:57.490Z")
],
"availableNow" : false,
"mainSkills" : "MM"
,
]
有什么想法吗？谢谢！
@eol 解决的问题 - 简单说明
如前所述，@eol 解决了问题并分享了解决方案。我接受了他的回答并将其翻译成 JavaScript/Mongoose sintaxis，就这样：
interviewRouter.get(
"/:idCandidato&:userEmail",
async (req: Request, res: Response) =>
const idCandidato, userEmail = req.params;
const infoCandidato = await User.aggregate([
"$match":
email: userEmail
,
"$unwind": "$candidates"
,
"$match":
"candidates.candidateId": parseInt(idCandidato)
]);
infoCandidato.length !== 0
infoCandidato
? res.status(200).json( Candidato: infoCandidato )
: res.status(404).json( Candidato: "Candidato no encontrado" );
);
【问题讨论】：
【参考方案1】：您可以进行简单的聚合，首先$match 具有给定email 的文档，然后$unwind 候选元素和过滤器$match 给定id 的那些：
db.collection.aggregate([
"$match":
email: "random@email.com"
,
"$unwind": "$candidates"
,
"$match":
"candidates.candidateId": 1234
])
这是 mongoplayground 上的一个示例：https://mongoplayground.net/p/GPB3oYqe5em
【讨论】：
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