seed.js

const db = require("./models");

// Delete All Trips
console.log('Deleting all trips...');

db.Trip.deleteMany({}, (err, result) => {
  if (err) {
    console.log(err);
    process.exit();
  }

  console.log(`Successfully deleted ${result.deletedCount} trips.`);

  // Delete All Stops
  console.log('Deleting all stops...');
  db.Stop.deleteMany({}, (err, result) => {
    if (err) {
      console.log(err);
      process.exit();
    }

    console.log(`Successfully deleted ${result.deletedCount} stops.`);

    // Delete All Users
    console.log('Deleting all users...');

    db.User.deleteMany({}, (err, result) => {
      if (err) {
        console.log(err);
        process.exit();
      };

      console.log(`Successfully deleted ${result.deletedCount} users.`);

      // Create New Trips
      console.log('Creating new trips...');
      db.Trip.create(cities, (err, newTrips) => {
        if (err) {
          console.log(err);
          process.exit();
        };

        console.log(`Successfully created ${newTrips.length} trips.`);
        process.exit();
      });
    });
  });
});