private static async Task AddTwoRecordsWithTwoTxAsync()
{
WriteLine(nameof(AddTwoRecordsWithTwoTxAsync));
try
{
using (var context = new MenusContext())
{
WriteLine("adding two records with two transactions to the database. One record should be written, the other not....");
var card = context.MenuCards.First();
var m1 = new Menu { MenuCardId = card.MenuCardId, Text = "added", Price = 99.99m };
context.Menus.Add(m1);
int records = await context.SaveChangesAsync();
WriteLine($"{records} records added");
int hightestCardId = await context.MenuCards.MaxAsync(c => c.MenuCardId);
var mInvalid = new Menu { MenuCardId = ++hightestCardId, Text = "invalid", Price = 999.99m };
context.Menus.Add(mInvalid);
records = await context.SaveChangesAsync();
WriteLine($"{records} records added");
}
}
catch (DbUpdateException ex)
{
WriteLine($"{ex.Message}");
WriteLine($"{ex?.InnerException.Message}");
}
WriteLine();
}
private static async Task AddTwoRecordsWithOneTxAsync()
{
WriteLine(nameof(AddTwoRecordsWithOneTxAsync));
try
{
using (var context = new MenusContext())
{
var card = context.MenuCards.First();
var m1 = new Menu { MenuCardId = card.MenuCardId, Text = "added", Price = 99.99m };
int hightestCardId = await context.MenuCards.MaxAsync(c => c.MenuCardId);
var mInvalid = new Menu { MenuCardId = ++hightestCardId, Text = "invalid", Price = 999.99m };
context.Menus.AddRange(m1, mInvalid);
WriteLine("trying to add one invalid record to the database, this should fail...");
int records = await context.SaveChangesAsync();
WriteLine($"{records} records added");
}
}
catch (DbUpdateException ex)
{
WriteLine($"{ex.Message}");
WriteLine($"{ex?.InnerException.Message}");
}
WriteLine();
}
public static async Task PreparationAsync()
{
using (var context = new MenusContext())
{
bool deleted = await context.Database.EnsureDeletedAsync();
string deletedText = deleted ? "deleted" : "does not exist";
WriteLine($"database {deletedText}");
bool created = await context.Database.EnsureCreatedAsync();
string createdText = created ? "created" : "already exists";
WriteLine($"database {createdText}");
var card = new MenuCard() { Title = "Meat" };
var m1 = new Menu { MenuCard = card, Text = "Wiener Schnitzel", Price = 12.90m };
var m2 = new Menu { MenuCard = card, Text = "Goulash", Price = 8.80m };
card.Menus.AddRange(new Menu[] { m1, m2 });
context.MenuCards.Add(card);
int records = await context.SaveChangesAsync();
WriteLine($"{records} records added");
}
}
private static async Task UpdateUntrackedAsync(Menu m)
{
using (var context = new MenusContext())
{
ShowState(context);
//EntityEntry<Menu> entry = context.Menus.Attach(m);
//entry.State = EntityState.Modified;
context.Menus.Update(m);
ShowState(context);
await context.SaveChangesAsync();
}
}
private static async Task TwoSaveChangesWithOneTxAsync()
{
WriteLine(nameof(TwoSaveChangesWithOneTxAsync));
IDbContextTransaction tx = null;
try
{
using (var context = new MenusContext())
using (tx = await context.Database.BeginTransactionAsync())
{
WriteLine("using one explicit transaction, writing should roll back...");
var card = context.MenuCards.First();
var m1 = new Menu { MenuCardId = card.MenuCardId, Text = "added with explicit tx", Price = 99.99m };
context.Menus.Add(m1);
int records = await context.SaveChangesAsync();
WriteLine($"{records} records added");
int hightestCardId = await context.MenuCards.MaxAsync(c => c.MenuCardId);
var mInvalid = new Menu { MenuCardId = ++hightestCardId, Text = "invalid", Price = 999.99m };
context.Menus.Add(mInvalid);
records = await context.SaveChangesAsync();
WriteLine($"{records} records added");
tx.Commit();
}
}
catch (DbUpdateException ex)
{
WriteLine($"{ex.Message}");
WriteLine($"{ex?.InnerException.Message}");
WriteLine("rolling back...");
tx.Rollback();
}
WriteLine();
}
