Use command line nodeJS to drop, create, and seed a mongoDB database

2014-10-01-use-command-line-nodejs-to-drop-create-and-seed-a-mongodb-database.js

// Utility library for handlng asynchronous calls
var async = require('async');

// URL to connect to a local MongoDB with database test
var databaseURL = 'mongodb://localhost:27017/test';

// We use mongoose to define our schema and interact with MongoDB
var mongoose = require('mongoose');
var bcrypt = require('bcrypt-nodejs');

// Define User schema model with 3 fields: user, email, password
var userSchema = new mongoose.Schema({
  name: { type: String, required: "Name is required",  },    
  email: { type: String, required: "Email is required", unique: true },
  password: { type: String, required: "Your password is required"},
});

// Mongoose middleware that is called before save to hash the password
userSchema.pre('save', function(next, err) {

 var user = this;
 var SALT_FACTOR = 10;

 // If user is not new or the password is not modified
 if (!user.isNew && !user.isModified('password')) {
   return next();
 }

 // Encrypt password before saving to database
 bcrypt.genSalt(SALT_FACTOR, function(err, salt) {

   if (err) return next(err);

   bcrypt.hash(user.password, salt, null, function(err, hash) {
     if (err) 
       return next(err);
     user.password = hash;
     next();
   });
 });
});

var User = mongoose.model('User', userSchema);

// User series method to make sure asynchronous calls below run serially
async.series([
  
  // First function - connect to MongoDB, then drop the database
  function(callback) {
    
    /**
     * Originally, I wanted to use mongoose to drop the database 
     * but the code below doesn't drop the database, only clears 
     * all documents. Refer to:
     *
     * https://github.com/LearnBoost/mongoose/issues/1654
     */
    /*
    mongoose.connection.on('open', function() { 
      mongoose.connection.db.dropDatabase(function(err) {
        if (err) console.log(err);
  
        mongoose.connection.close(function(err) {
          callback(null, 'Dropped database');
        });
      });
    });
    */
    
    // Conncect to MongoDB using the native MongoDB client for NodeJS
    var MongoClient = require('mongodb').MongoClient;
    MongoClient.connect(databaseURL, function(err, db) {

      if(err) throw err;
      
      // Drop database  
      db.dropDatabase();
      
      // Close database connection because we need to open a connection
      // with mongoose later to populate the database
      db.close();
      
      // Execute callback so next method in async.serial gets called
      callback(null, 'SUCCESS - dropped database');
    });
  },
  
  // Second function - connect to MongoDB using mongoose, which is an asynchronous call
  function(callback) {
    
    // Open connection to DB
    mongoose.connect(databaseURL);
    
    // Need to listen to 'connected' event then execute callback method
    // to call the next set of code in the async.serial array
    mongoose.connection.on('connected', function(){
      console.log('db connected via mongoose');
      callback(null, 'SUCCESS - Connected to mongodb');
    });
  },
  
  // Third function - use Mongoose to create a User model and save it to database
  function(callback) {

    // BEGIN SEED DATABASE
    
    // Use an array to store a list of User model objects to save to the database
    var users = [];
    var testUserCount = 20;
    for (i = 0; i < testUserCount; i++) {

      var user = new User({
        name: i,
        email: i + '@' + i + '.com',
        // Password will be hashed in the userSchema.pre middleware 
        password: 'asdfasdf'
      });

      // Add newly create User model to 'users' array
      users.push(user);
    }
    
    console.log("Populating database with %s users", users.length);

    // Use 'async.eachSeries' to loop through the users array 
    // to make sure each asnychronous call to save the user completes
    // before moving to the next User model item 
    
    async.eachSeries(
      
      // First parameter is the array to be iterated over
      users, 
      
      // 2nd param is the function that each item is passed to
      // Note there is another 'callback' method called asyncEachCallback
      function(user, asyncEachCallback){

        // There is no need to make a call to create the 'test' database
        // Saving a model will automatically create the database
        user.save(function(err) {

          if(err) {
            // Send JSON response to console for errors
            console.dir(err);
          }
          
          // Print out which user we are saving
          console.log("Saving user #%s out of %s", user.name, testUserCount);
          
          // Call 'ayncEachCallback' and NOT 'callback' to ensure that the next
          // 'user' item in the 'users' array gets called to be saved to the database
          asyncEachCallback();
        });

      },
      
      // 3rd param is the function to call when everything's done
      function(err){
        
        if (err) console.dir(err);
        
        // All tasks are done now
        console.log("Finished aysnc.each in seeding db")

        //Callback for async series call
        callback(null, 'SUCCESS - Seed database');

      }
    );

    // END SEED DATABASE

  }
],

// optional callback
function(err, results){
  
  console.log("\n\nExiting database seed");
  
  if(err) {
    console.log("Errors = ");
    console.dir(errors)
  } else {
  
    console.log("Results = ");
    console.log(results);
    
  }

  // Exit the process to get back to terrminal console 
  process.exit(0);
});