// Entity Framework Classic

// Doc: https://entityframework-classic.net/then-include

​

// @nuget: Z.EntityFramework.Classic

​

using System;

using System.Collections.Generic;

using System.Data.Entity;

using System.Linq;

​

public class Program

{

    public static void Main()

    {

        GenerateData();

​

        using (var context = new EntityContext())

        {

            var list = context.Customers

                .Include(customer => customer.Orders)

                    .ThenInclude(order => order.OrderDetails.Select(orderDetail => orderDetail.Product))

                .ToList();

​

            FiddleHelper.WriteTable("Customers", list);

            FiddleHelper.WriteTable("Orders", list.SelectMany(x => x.Orders).ToList()); 

            FiddleHelper.WriteTable("OrderDetails", list.SelectMany(x => x.Orders.SelectMany(y => y.OrderDetails)));    

            FiddleHelper.WriteTable("Products", list.SelectMany(x => x.Orders.SelectMany(y => y.OrderDetails.Select(z => z.Product))));         

        }

    }

    public static void GenerateData()

    {

        using (var context = new EntityContext())

        {

            // Supplier

            var supplier = context.Suppliers.Add(new Supplier() { Name = "ZZZ Projects" });

            // Category

            var category = context.Categories.Add(new Category() { Name = "EntityFramework", Description = "Entity Framework is an ORM made by Microsoft. It allows performing CRUD operations without having to write SQL queries. It supports Code First, Database First, Stored Procedure, Transaction, etc." });

            // Product

            var productEFClassic = context.Products.Add(new Product() { Name = "Entity Framework Classic", Category = category, Supplier = supplier });

            var productEFExtensions = context.Products.Add(new Product() { Name = "Entity Framework Extensions", Category = category, Supplier = supplier });

            // Customer

            var customer = context.Customers.Add(new Customer() { Name ="Customer_A", Description = "Description", IsActive = true, LastLogin = new DateTime(2010,1,1) });

            // Order

            var order = context.Order.Add(new Order() { Customer = customer, OrderDate = DateTime.Now, OrderDetails = new List<OrderDetail>() });

​

            // Order Detail

            order.OrderDetails.Add(new OrderDetail() { Product = productEFClassic, Quantity = 4 });

            order.OrderDetails.Add(new OrderDetail() { Product = productEFExtensions, Quantity = 19 });

            context.SaveChanges();  

        }

    }

​

    public class EntityContext : DbContext

    {

        public EntityContext() : base(FiddleHelper.GetConnectionStringSqlServer())

        {

​

        }

        public DbSet<Customer> Customers { get; set; }

        public DbSet<Order> Order { get; set; }

        public DbSet<OrderDetail> OrderDetails { get; set; }

        public DbSet<Product> Products { get; set; }

        public DbSet<Category> Categories { get; set; }

        public DbSet<Supplier> Suppliers { get; set; }

    }

    public class Customer

    {

        public int CustomerID { get; set; }

        public string Name { get; set; }

        public string Description { get; set; }

        public DateTime LastLogin { get; set; }

        public Boolean IsActive { get; set; }

        public List<Order> Orders { get; set; }

    }

    public class Order

    {

        public int OrderID { get; set; }

        public DateTime OrderDate { get; set; }

        public Customer Customer { get; set; }

        public List<OrderDetail> OrderDetails { get; set; }

    }

    public class OrderDetail

    {

        public int OrderDetailID { get; set; }

        public int Quantity { get; set; }

​

        public Product Product { get; set; }

    }

    public class Product

    {

        public int ProductID { get; set; }

        public string Name { get; set; }

        public Category Category { get; set; }

        public Supplier Supplier { get; set; }

    }

    public class Category

    {

        public int CategoryID { get; set; }

        public string Name { get; set; }

        public string Description { get; set; }

    }

    public class Supplier

    {

        public int SupplierID { get; set; }

        public string Name { get; set; }

    }

}