mongoose-issue

mongoose-callback.js

const mongoose = require('mongoose')

mongoose.connect('mongodb://localhost/test')

const schema = new mongoose.Schema({}, {strict: false})

const model = mongoose.model('test', schema)

model.collection.indexExists('users.user_1', (err, res) => {
  console.log(err, res)
  if (res) return model.collection.dropIndex('users.user_1')
})

mongoose-promise.js

const mongoose = require('mongoose')

mongoose.connect('mongodb://localhost/test')

const schema = new mongoose.Schema({}, {strict: false})

const model = mongoose.model('test', schema)

model.collection.indexExists('users.user_1')
  .then(async (res) => {
    if (res) return model.collection.dropIndex('users.user_1')
  })