仅在猫鼬.find()上返回文档_id [英] only return document _id on mongoose .find()

问题描述

我通过将新数据推送到文档中的数组来每秒更新100多个文档.为了获得要添加数据的文档，我使用了mongoose .find().limit(1)函数，并返回了整个文档.它工作正常.

I update 100's of documents every second by pushing new data to an array in its document. To get the document of which I am going to add data to, I use the mongoose .find().limit(1) function, and return the whole document. It works fine.

为了帮助解决一些内存和cpu问题，我想知道如何让find()只返回文档的id，以便可以将其用于$ push或$ set新数据.

To help with some memory and cpu issues I have, I was wondering how I could get find() to only return the id of the document so I can use that to $push or $set new data.

谢谢.

推荐答案

您要使用

You want to use Projection to tell your query exactly what you want off of your objects.

_id，否则始终将其包括在内.

_id is always included unless you tell it not to.

readings = await collection
.find({
    name: "Some name you want"
})
.project({
    _id: 1 // By default
})
.toArray();

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