put models in file not schema

db/index.js

@@ -1,24 +1,25 @@
-import mongoose from 'mongoose'
-import { BookingSchema, BookerSchema } from './schema'
+import * as mongoose from 'mongoose'
 
-mongoose.connect(process.env.MONGO_URI, {
-  useNewUrlParser: true,
-  useUnifiedTopology: true,
-  connectTimeoutMS: 1000,
-  serverSelectionTimeoutMS: 5000,
-})
+import Booker from './booker'
+import Booking from './booking'
 
-if (process.env.NODE_ENV !== 'production') {
-  mongoose.modelNames().includes('Booker') && mongoose.deleteModel('Booker')
-  mongoose.modelNames().includes('Booking') && mongoose.deleteModel('Booking')
+let connectedPromise
+
+function connect() {
+  if (connectedPromise) {
+    return
+  }
+
+  connectedPromise = mongoose.connect(process.env.MONGO_URI, {
+    useNewUrlParser: true,
+  })
+
+  return connectedPromise
 }
 
-export const Booker =
-  mongoose.models.Booker || mongoose.model('Booker', BookerSchema)
-export const Booking =
-  mongoose.models.Booking || mongoose.model('Booking', BookingSchema)
-
 export async function getBookedDays() {
+  await connect()
+
   const bookings = await Booking.find(
     {
       status: { $ne: 'rejected' },
@@ -48,6 +49,7 @@ export async function createBooking({
   zip,
   city,
 }) {
+  await connect()
   const booking = new Booking({ startDate, endDate, purpose, org, destination })
   const bookedDays = await getBookedDays()