ASPNetCore/TestAppRuna/Services/CartService.cs

using Microsoft.EntityFrameworkCore;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using TestAppRuna.API;
using TestAppRuna.Entities;

namespace TestAppRuna.Services
{
    public class CartService : ICartService
    {
        public CartService(ShopDbContext shopDbContext)
        {
            this.DB = shopDbContext;
        }

        public ShopDbContext DB { get; }

        public async Task<bool> CreateOrUpdateCart(CartCreateUpdateModel model)
        {
            Cart cart = await DB.Carts
                .Where(Q => Q.CustomerID == model.CustomerID && Q.ProductID == model.ProductID)
                .FirstOrDefaultAsync();
            if (cart == null)
            {
                cart = new Cart
                {
                    ProductID = model.ProductID,
                    CustomerID = model.CustomerID,
                };
                DB.Carts.Add(cart);
            }
            cart.Quantity = model.Quantity;

            await DB.SaveChangesAsync();
            return true;
        }

        public async Task<bool> DeleteCart(CartDeleteModel model)
        {
            var data = await DB.Carts
                .Where(Q => Q.CustomerID == model.CustomerID && Q.ProductID == model.ProductID)
                .FirstOrDefaultAsync();
            if (data == null)
            {
                return false;
            }
            DB.Carts.Remove(data);
            await DB.SaveChangesAsync();
            return true;
        }

        public async Task<List<CartCustomerListItem>> Get()
        {
            var query = from cart
                       in DB.Carts
                        join product in DB.Products on cart.ProductID equals product.ProductID
                        join customer in DB.Customers on cart.CustomerID equals customer.CustomerID
                        select new CartCustomerListItem
                        {
                            ProductID = cart.ProductID,
                            ProductName = product.Name,
                            ProductPrice = product.Price,
                            CustomerEmail = customer.Email,
                            CustomerName = customer.Name,
                            Quantity = cart.Quantity,
                        };
            var data = await query.ToListAsync();
            return data;
        }

        public async Task<List<CartListItem>> GetFromCustomer(Guid customerId)
        {
            var data = await DB.Carts
                .AsNoTracking()
                .Where(Q => Q.CustomerID == customerId)
                .Select(Q => new CartListItem
                {
                    ProductID = Q.ProductID,
                    ProductName = Q.Product.Name,
                    ProductPrice = Q.Product.Price,
                    Quantity = Q.Quantity
                }).ToListAsync();
            return data;
        }

        public async Task<bool> HasCustomerID(Guid customerId)
        {
            return await DB.Customers
                .AsNoTracking()
                .Where(Q => Q.CustomerID == customerId)
                .AnyAsync();
        }

        public async Task<bool> HasProductID(Guid productId)
        {
            return await DB.Products
                .AsNoTracking()
                .Where(Q => Q.ProductID == productId)
                .AnyAsync();
        }
    }
}