title: db.collection.remove() function not working on MongoDB using Node.js
body: <p>I just had a quick question about a problem I have been running into with MongoDB using Node.js. I am not able to delete all the documents in a collection using the command "db.users.remove({})". I know that the collection name is correct. I have run this in the terminal and although it seems as though the command was run, it did not delete all the documents in the collection. When I run it using a post request, it just says db is not defined, which makes no sense to me. The reason why I have no query string is that I want to delete all the documents. I have included all my code below, but if a person can tell me perhaps a better way to delete all the documents in a collection or a solution to my problem I will greatly appreciate it. Thanks!</p>
  
  <pre><code>const fs = require('fs')
  const express = require('express')
  const router = express.Router()
  const checkTypes = require('checktypes-js')
  const schema = require('../schemas/user')
  const usersDB = require('../models/usersModel')
  const { Types } = require('mongoose')
  
  const fileQuery = "logs.txt"
  
  
  router.post('/new', (req, res) =&gt; {
      checkTypes(req.body, schema.user, async (err, passedObject) =&gt; {
          if (err){
              console.log(err)
              return res.json({errors: err})
          } else {
              const existingUserEmail = await usersDB.findOne({email: passedObject.email})
              const existingUserUsername = await usersDB.findOne({username: passedObject.username})
              console.log(existingUserEmail, existingUserUsername)
              if (existingUserEmail || existingUserUsername){
                  return res.json({error: "A user with that email or username exists too!"})
              }
              passedObject.active = true
              const addedUser = await usersDB.create(passedObject)
              res.send(addedUser)
              const fileMessage = "\nNew user with username of " + existingUserUsername + ' has been added on ' + new Date()
              console.log(fileMessage)
              return fs.appendFile(fileQuery, fileMessage, function (err){
                  if (err){
                      console.error(err)
                  }
                  res.send("The file has been successfully written to!")
              })
          } 
      })
  })
  
  router.post('/update', (req, res) =&gt; {
      checkTypes(req.body, schema.user, async (err, passedObject) =&gt; {
          if (err){
              console.log(err)
              return res.json({errors: err})
          } else {
              const {_id, ...update} = passedObject
              if(!Types.ObjectId.isValid(_id)){
                  return res.json({error: 'Invalid id supplied'})
              }
              const updatedUser = await usersDB.findByIdAndUpdate(_id, update, {new: true})
              if (!updatedUser){
                  return res.json({error: "Could not find the user with that ID!"})
              } else {
                  res.json(updatedUser)
                  const fileMessage = "\nUpdate user with id of " + _id + ' on ' + new Date()
                  console.log(fileMessage)
                  return fs.appendFile(fileQuery, fileMessage, function (err){
                      if (err){
                          console.error(err)
                      }
                      res.send("The file has been successfully written to!")
                  })
              }
          }
      })
  })
  
  router.post("/delete", (req, res) =&gt; {
      checkTypes(req.body, schema.user, async (err, passedObject) =&gt; {
          if (err){
              console.log(err)
              res.json({error: err})
          } else {
              const {_id, ...deleteObj} = passedObject
              console.log(_id)
              if(!Types.ObjectId.isValid(_id)){
                  return res.json({error: 'Invalid id supplied'})
              }
              const deleteUser = usersDB.findByIdAndRemove({_id: _id}, function (err){
                  if (err){
                      return res.send("A user with that ID is not defined!")
                  } else {
                      res.send("The object has been deleted!")
                      const fileMessage = "\nUser with id of " + _id + ' has been delete on ' + new Date()
                      console.log(fileMessage)
                      return fs.appendFile(fileQuery, fileMessage, function (err){
                          if (err){
                              console.error(err)
                          }
                          res.send("The file has been successfully written to!")
                      })
                  }
              })
          }
      })
  })
  
  router.post("/deleteAll", (req, res) =&gt; {
      db.users.remove({})
      res.send("All documents have been deleted!")
      const fileMessage = "\nAll documents in the remindars collection have been deleted on " + new Date()
          console.log(fileMessage)
          return fs.appendFile(fileQuery, fileMessage, function (err){
              if (err){
                  console.error(err)
              }
              res.send("The file has been successfully written to!")
          })
  })
  
  router.post('/testFile', (req, res) =&gt; {
      const fileMessage = "\nThe file writing script was tested on " + new Date()
      console.log(fileMessage)
      return fs.appendFile(fileQuery, fileMessage, function (err){
          if (err){
              console.error(err)
          }
          res.send("The file has been successfully written to!")
      })
  })
  
  router.post('/clearFile', (req, res) =&gt; {
      const fileMessage = ""
      console.log(fileMessage)
      return fs.writeFile(fileQuery, fileMessage, function (err){
          if (err){
              console.error(err)
          }
          res.send("The file has been successfully written to!")
      })
  })
  
  module.exports = router
  </code></pre>