private static async Task CreateDatabaseAsync()
{
using (var context = new BooksContext())
{
bool created = await context.Database.EnsureCreatedAsync();
string createdText = created ? "created" : "already exists";
WriteLine($"database {createdText}");
}
}
private void ReadBooks()
{
using (var context = new BooksContext())
{
var books = context.Books;
foreach (var b in books)
{
WriteLine($"{b.Title} {b.Publisher}");
}
}
WriteLine();
}
private async Task AddBookAsync(string title, string publisher)
{
using (var context = new BooksContext())
{
var book = new Book { Title = title, Publisher = publisher };
context.Add(book);
int records = await context.SaveChangesAsync();
WriteLine($"{records} record added");
}
WriteLine();
}
private static async Task AddBookAsync()
{
using (var context = new BooksContext())
{
var b = new Book { Title = BookTitle, Publisher = "Sample" };
context.Add(b);
int records = await context.SaveChangesAsync();
WriteLine($"{records} record added");
}
WriteLine();
}
static void Main()
{
using (var context = new BooksContext())
{
context.Database.EnsureCreated();
if (context.Books.Count() == 0)
{
var b1 = new Book { Title = "Professional C# 6 and .NET Core 1.0", Publisher = "Wrox Press" };
var b2 = new Book { Title = "Professional C# 5 and .NET 4.5.1", Publisher = "Wrox Press" };
var b3 = new Book { Title = "JavaScript for Kids", Publisher = "Wrox Press" };
var b4 = new Book { Title = "Web Design with HTML and CSS", Publisher = "For Dummies" };
context.Books.AddRange(b1, b2, b3, b4);
}
}
}
private async Task AddBooksAsync()
{
using (var context = new BooksContext())
{
var b1 = new Book { Title = "Professional C# 5 and .NET 4.5.1", Publisher = "Wrox Press" };
var b2 = new Book { Title = "Professional C# 2012 and .NET 4.5", Publisher = "Wrox Press" };
var b3 = new Book { Title = "JavaScript for Kids", Publisher = "Wrox Press" };
var b4 = new Book { Title = "Web Design with HTML and CSS", Publisher = "For Dummies" };
var b5 = new Book { Title = "Conflict Handling", Publisher = "Test" };
context.AddRange(b1, b2, b3, b4, b5);
int records = await context.SaveChangesAsync();
WriteLine($"{records} records added");
}
WriteLine();
}
private void QueryBooks()
{
using (var context = new BooksContext())
{
var wroxBooks = context.Books.Where(b => b.Publisher == "Wrox Press");
// comment the previous line and uncomment the next lines to try the LINQ query syntax
//var wroxBooks = from b in context.Books
// where b.Publisher == "Wrox Press"
// select b;
foreach (var b in wroxBooks)
{
WriteLine($"{b.Title} {b.Publisher}");
}
}
WriteLine();
}
public BooksService(BooksContext context)
{
_booksContext = context;
}
private async Task UpdateBookAsync()
{
using (var context = new BooksContext())
{
int records = 0;
var book = context.Books.Where(b => b.Title == "Professional C# 6").FirstOrDefault();
if (book != null)
{
book.Title = "Professional C# 6 and .NET Core 5";
records = await context.SaveChangesAsync();
}
WriteLine($"{records} record updated");
}
WriteLine();
}
private static async Task CheckUpdateAsync(int id)
{
using (var context = new BooksContext())
{
Book book = await context.Books.Where(b => b.BookId == id).FirstOrDefaultAsync();
WriteLine($"updated: {book.Title}");
}
}
private static async Task UpdateAsync(BooksContext context, Book book)
{
await context.SaveChangesAsync();
WriteLine($"successfully written to the database: id {book.BookId} with title {book.Title}");
}
private static async Task<Tuple<BooksContext, Book>> PrepareUpdateAsync()
{
var context = new BooksContext();
Book book = await context.Books.Where(b => b.Title == "Conflict Handling").FirstOrDefaultAsync();
return Tuple.Create(context, book);
}
private async Task DeleteBooksAsync()
{
using (var context = new BooksContext())
{
var books = context.Books;
context.Books.RemoveRange(books);
int records = await context.SaveChangesAsync();
WriteLine($"{records} records deleted");
}
WriteLine();
}
private static void Update(BooksContext context, Book book, string user)
{
int records = context.SaveChanges();
Console.WriteLine($"{user}: {records} record updated from {user}");
}
private static async Task UpdateAsync(BooksContext context, Book book, string user)
{
try
{
WriteLine($"{user}: updating id {book.BookId}, timestamp {book.TimeStamp.StringOutput()}");
ShowChanges(book.BookId, context.Entry(book));
int records = await context.SaveChangesAsync();
WriteLine($"{user}: updated {book.TimeStamp.StringOutput()}");
WriteLine($"{user}: {records} record(s) updated while updating {book.Title}");
}
catch (DbUpdateConcurrencyException ex)
{
WriteLine($"{user} update failed with {book.Title}");
WriteLine($"{user} error: {ex.Message}");
foreach (var entry in ex.Entries)
{
Book b = entry.Entity as Book;
WriteLine($"{b.Title} {b.TimeStamp.StringOutput()}");
ShowChanges(book.BookId, context.Entry(book));
}
}
}
private static async Task UpdateAsync(BooksContext context, Book book)
{
await context.SaveChangesAsync();
WriteLine($"successfully written to the database: id {book.BookId} with title {book.Title}");
}
