如何在不检索的情况下检查文档是否存在：猫鼬

Question

I am using Mongoose to connect to MongoDB and perform CRUD operations on it. One of my collections has a lot of data in its individual documents (records). At a point in my code, I want to check if a document with particular id field exists already in the collection, and if it does, then I can show a proper error to the user.

Currently, I am using the findOne() method available in the Mongoose library. The problem with this method (or any other find prefixed methods) is that it retrieves the data, which takes a bit time if there is a crazy bunch of data stored.

I am looking for a way to get some kind of boolean as a result indicating if the document exists or not, without actually getting the whole document itself.

Answer 1

Alternatively you could use countDocuments() to check the number of documents in the query? This will just count the number rather than returning it.

Answer 2

Pass id in findOne()

Make a one common function.

const objectID = require('mongodb').ObjectID
getMongoObjectId(id) {   
    return new objectID(id)
}

Now just call function

findOne({_id:common.getMongoObjectId('ID value hear')})

It will same as where condition in mysql.