// @nuget: EntityFramework

​

using System;

using System.Data.Entity;

using System.Linq;

using System.Collections.Generic;

using System.ComponentModel.DataAnnotations.Schema;

​

​

public class Program

{

    public static void Main()

    {

        InsertData();

        Category programmingCat;

        using(var context = new BookStore())

        {

            DisplayData(context.Authors.ToList());

            programmingCat = context.Categories

                .Where(c => c.CategoryId == 2)

                .FirstOrDefault();

        }

        Book book = new Book()

        {

            Title = "iOS Fundamentals",

​

            Author = new Author()

            {

                AuthorId = 1,

                Name = "Mark"

            },

            Categories = new List<Category>()

            {

                programmingCat, 

                new Category() { CategoryName = "iOS"},

                new Category() { CategoryName = "Swift"}

            }

        };

        InsertOrUpdate(book);

        using(var context = new BookStore())

        {

            Console.WriteLine("\n\n\nAfter Entity Graph\n\n\n");

            DisplayData(context.Authors.ToList());

        }

    }

    public static void InsertOrUpdate(Book book)

    {

        using(var context = new BookStore())

        {

            context.Entry(book).State = book.BookId == 0 ? 

                EntityState.Added : EntityState.Modified;

​

            context.Entry(book.Author).State = book.Author.AuthorId == 0 ? 

                EntityState.Added : EntityState.Modified;

​

            foreach (var cat in book.Categories)

            {

                context.Entry(cat).State = cat.CategoryId == 0 ? 

                    EntityState.Added : EntityState.Modified;

            }

            context.SaveChanges();

        }

    }

    public static void DisplayData(List<Author> list)

    {

        foreach(var author in list)

        {

            Console.WriteLine("Author Name: " + author.Name);

            Console.WriteLine("\tBook List:");

            foreach(var book in author.Books)

            {

                Console.WriteLine("\t\t" + book.Title);

            }

        }

    }

    public static void InsertData()

    {

        using (var context = new BookStore())

        {

            Category c1 = new Category() { CategoryName = "C#" };

            Category c2 = new Category() { CategoryName = "Programming" };

            Category c3 = new Category() { CategoryName = "Java" };

            Category c4 = new Category() { CategoryName = "SQL" };

            Category c5 = new Category() { CategoryName = "VB.NET" };

​

            Author author1 = new Author()

            {

                Name = "Mark",

                Books = new List<Book>

                {

                    new Book() { Title = "Fundamentals of Computer Programming with C#", Categories = new List<Category>(){c1, c2}},

                    new Book() { Title = "Java: A Beginner's Guide", Categories = new List<Category>(){c3, c2}},

                }

            };

            Author author2 = new Author()

            {

                Name = "Andy",

                Books = new List<Book>

                {

                    new Book() { Title = "SQL: The Ultimate Beginners Guide", Categories = new List<Category>(){c4}}

                }

            };

            Author author3 = new Author()

            {

                Name = "Johny",

                Books = new List<Book>

                {

                    new Book() { Title = "Learn VB.NET", Categories = new List<Category>(){c5, c2}},

                    new Book() { Title = "C# Fundamentals for Absolute Beginners", Categories = new List<Category>(){c1, c2}},

                }

            };

            context.Authors.Add(author1);

            context.Authors.Add(author2);

            context.Authors.Add(author3);

​

            context.SaveChanges();

        }

    }

    public class BookStore : DbContext

    {

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

        {

        }

​

        public DbSet<Author> Authors { get; set; }

        public DbSet<Book> Books { get; set; }

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

    }

​

     public class Book

    {

        public int BookId { get; set; }

        public string Title { get; set; }

        public int AuthorId { get; set; }

        [ForeignKey("AuthorId")]

        public Author Author { get; set; }

        public virtual ICollection<Category> Categories { get; set; }

    }

​

    public class Author

    {

        public int AuthorId { get; set; }

        public string Name { get; set; }

        public virtual ICollection<Book> Books { get; set; }

    }

    public class Category

    {

        public int CategoryId { get; set; }

        public string CategoryName { get; set; }

        public virtual ICollection<Book> Books { get; set; }

    }

}