GayanM

database = postgres             # Determines which of PostgreSQL or Cassandra
                                 # this node will use as its datastore.
                                 # Accepted values are `postgres`,
                                 # `cassandra`, and `off`.

pg_host = 127.0.0.1             # Host of the Postgres server.
pg_port = 5432                  # Port of the Postgres server.
pg_timeout = 5000               # Defines the timeout (in ms), for connecting,
                                 # reading and writing.

GayanM

    @RequestMapping("/most-expensive")
    Map<String, Optional<Product>> getMostExpensiveProductByCategory () {
        Map<String, Optional<com.mycompany.functional.programming.exercises.models.Product>> mostExpensiveByCategory = productRepos.findAll().stream().collect(Collectors.groupingBy(
                    com.mycompany.functional.programming.exercises.models.Product::getCategory,
                    Collectors.maxBy(Comparator.comparing(com.mycompany.functional.programming.exercises.models.
                            Product::getPrice)
                 )
         ));
        Map<String, Optional<Product>> ordersByCustomerTransformed = new HashMap();
        mostExpensiveByCategory.entrySet().stream().forEach(e -> {

GayanM

    @RequestMapping("/product-category")
    Map<String, List<String>> getProductsByCategory(List<Product> productList) {
        return productRepos.findAll().stream().collect(Collectors.groupingBy(com.mycompany.functional.programming.
                        exercises.models.Product::getCategory, Collectors.mapping(product -> product.getName(),
                Collectors.toList())));
    }

GayanM

    @RequestMapping("/product-total-sum")
    public Map<Order, Double> getProductTotalSumByOrder() {
         return orderRepo.findAll().stream().collect(Collectors.toMap(o -> new Order(o.getId(), o.getOrderDate(),
                 o.getDeliveryDate(), o.getStatus()), o -> o.getProducts().stream().mapToDouble(p ->
                 p.getPrice()).sum()));
    }

GayanM

    @RequestMapping("/group-by-customer")
    public Map<Customer, List<Order>> getOrdersByCustomer () {
        Map<com.mycompany.functional.programming.exercises.models.Customer,
                List<com.mycompany.functional.programming.exercises.models.Order>> ordersByCustomer = orderRepo.
                findAll().stream().collect(Collectors.groupingBy(com.mycompany.functional.programming.exercises.models.
                        Order::getCustomer));
        Map<Customer, List<Order>> ordersByCustomerTransformed = new HashMap();
        ordersByCustomer.forEach((k,v) -> {
            Customer customer = new Customer(k.getId(), k.getName(), k.getTier());
            List<Order> orders = v.stream().map(o -> new Order(o.getId(), o.getOrderDate(), o.getDeliveryDate(), o.getStatus())).

GayanM

    @RequestMapping("/products-count")
    public Map<Long, Integer> getOrdersWithProductCount() {
        return orderRepo.findAll().stream().
                collect(Collectors.toMap(o -> o.getId(), o -> o.getProducts().size()));
    }

GayanM

    @RequestMapping("/statistics")
    public DoubleSummaryStatistics getStatistics(@RequestParam("category") final Optional<String> category) {
        return productRepos.findAll().stream().filter(p -> category.get().equalsIgnoreCase(p.getCategory())).
                mapToDouble(p -> p.getPrice()).summaryStatistics();
    }

GayanM

    @RequestMapping("/avg-payment")
    public Double getAvgPayment(@RequestParam("date") final Optional<String> date) {
        DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd");
        return orderRepo.findAll().stream().filter(o -> o.getOrderDate().isEqual(LocalDate.
                        parse(date.get(), formatter))).flatMap(o -> o.getProducts().stream()).mapToDouble(p ->
                p.getPrice()).average().getAsDouble();
    }

GayanM

    @RequestMapping("/lump-sum")
    public Double lumpSumOfOrders (@RequestParam("month") final int month) {
        return orderRepo.findAll()
                .stream()
                .filter(o -> o.getOrderDate().compareTo(LocalDate.of(2021, month, 1)) >= 0)
                .filter(o -> o.getOrderDate().compareTo(LocalDate.of(2021, month + 1, 1)) < 0)
                .flatMap(o -> o.getProducts().stream())
                .mapToDouble(p -> p.getPrice())
                .sum();

GayanM

  
    @RequestMapping("/log-orders")
    public List<Product> logOrdersOnGivenDateAndReturnProducts(@RequestParam("date") final Optional<String> date) {
        DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd");
        return orderRepo.findAll().stream()
                .filter(o -> o.getOrderDate().isEqual(LocalDate.parse(date.get(), formatter)))
                .peek(o -> System.out.println(o.toString()))
                .flatMap(o -> o.getProducts().stream())
                .distinct().map(p -> new Product(p.getId(), p.getName(), p.getPrice(), p.getCategory()))
                .collect(Collectors.toList());