NodeJS的DDD與CRUD對比案例 - Khalil Stemmler

const numbers = [1,2,3,4,5];
let max = -1;
for (let i = 0; i < numbers.length; i++) {
  if (numbers[i] > max) {   
    max = numbers[i] 
  }
}

const numbers = [1,2,3,4,5]
const max = numbers.reduce((a,b) => Math.max(a,b))

class MovieController {
  public async rentMovie (movieId: string, customerId: string) {
    // Sequelize ORM models
    const { Movie, Customer, RentedMovie, CustomerCharge } = this.models;

    // Get the raw orm records from Sequelize
    const movie = await Movie.findOne({ where: { movie_id: movieId }});
    const customer = await Customer.findOne({ where: { customer_id: customerId }});

    // 401 error if not found
    if (!!movie === false) {
      return this.notFound('Movie not found')
    }

    // 401 error if not found
    if (!!customer === false) {
      return this.notFound('Customer not found')
    }

    // Create a record which signified a movie was rented
    await RentedMovie.create({
      customer_id: customerId,
      movie_id: movieId
    });

    // Create a charge for this customer.
      await CustomerCharge.create({
      amount: movie.rentPrice
    })

    return this.ok();
  }
}

class MovieController extends BaseController {
  constructor (models) {
    super();
    this.models = models;
  }
  public async rentMovie () {
    const { req } = this;
    const { movieId } = req.params['movie'];
    const { customerId } = req.params['customer'];

    // We need to pull out one more model,
    // CustomerPayment
    const { 
      Movie, 
      Customer, 
      RentedMovie, 
      CustomerCharge, 
      CustomerPayment 
    } = this.models;

    const movie = await Movie.findOne({ where: { movie_id: movieId }});
    const customer = await Customer.findOne({ where: { customer_id: customerId }});

    if (!!movie === false) {
      return this.notFound('Movie not found')
    }

    if (!!customer === false) {
      return this.notFound('Customer not found')
    }

    // Get the number of movies that this user has rented
    const rentedMovies = await RentedMovie.findAll({ customer_id: customerId });
    const numberRentedMovies = rentedMovies.length;

    // Enforce the rule
    if (numberRentedMovies >= 3) {
      return this.fail('Customer already has the maxiumum number of rented movies');
    }

    // Get all the charges and payments so that we can 
    // determine if the user still owes money
    const charges = await CustomerCharge.findAll({ customer_id: customerId });
    const payments = await CustomerPayment.findAll({ customer_id: customerId });

    const chargeDollars = charges.reduce((previousCharge, nextCharge) => {
      return previousCharge.amount + nextCharge.amount;
    });

    const paymentDollars = payments.reduce((previousPayment, nextPayment) => {
      return previousPayment.amount + nextPayment.amount;
    })

    // Enforce the second business rule
    if (chargeDollars > paymentDollars) {
      return this.fail('Customer has outstanding balance unpaid');
    }

    // If all else is good, we can continue
    await RentedMovie.create({
      customer_id: customerId,
      movie_id: movieId
    });
    
    await CustomerCharge.create({
      amount: movie.rentPrice
    })

    return this.ok();
  }
}

class MovieController extends BaseController {
  private movieRepo: IMovieRepo;
  private customerRepo: ICustomerRepo;
  
  constructor (movieRepo: IMovieRepo, customerRepo: ICustomerRepo) {
    super();
    this.movieRepo = movieRepo;
    this.customerRepo = customerRepo;
  }

  public async rentMovie () {
    const { req, movieRepo, customerRepo } = this;
    const { movieId } = req.params['movie'];
    const { customerId } = req.params['customer'];

    const movie: Movie = await movieRepo.findById(movieId);
    const customer: Customer = await customerRepo.findById(customerId);

    if (!!movie === false) {
      return this.fail('Movie not found')
    }

    if (!!customer === false) {
      return this.fail('Customer not found')
    }

    // The declarative magic happens here.
    const rentMovieResult: Result<Customer> = customer.rentMovie(movie);

    if (rentMovieResult.isFailure) {
      return this.fail(rentMovieResult.error)
    } else {
      // if we were using the Unit of Work pattern, we wouldn't 
      // need to manually save the customer at the end of the request.
      await customerRepo.save(customer);
      return this.ok();
    }
  }
}