javascript - MongoDB find() and retrieve only a field of all documents

Question

Why does opening this API/test page log the whole documents inside Users collection instead of only names?

import { connectToDatabase } from "../../utils/mongodb"

export default async (req, res) => {
  const { db } = await connectToDatabase();

  try{
    const userNames = await db.collection('Users').find({}, {name: 1, _id: 0}).toArray()
    
    console.log('userNames '+JSON.stringify(userNames))

  }catch(err){
    console.log(err)
  }
}

Answer 1

It seems you're using mongodb v3. While the syntax you used above worked in v2, v3 no longer supports the fields parameter. You either need to pass the projection property in on the options object or include a projection document to specify or restrict fields to return, like .project({ name: 1, _id: 0 }).

const userNames = await db.collection('Users')
  .find({})
  .project({ name: 1, _id: 0 })
  .toArray()

// OR

const userNames = await db.collection('Users')
  .find(
    {}, 
    { projection: { name: 1, _id: 0 } }
   )
  .toArray()

More changes in MongoDB v3: https://github.com/mongodb/node-mongodb-native/blob/master/CHANGES_3.0.0.md