private static void AddTwoRecordsWithTwoTx()
{
Console.WriteLine(nameof(AddTwoRecordsWithTwoTx));
try
{
using (var context = new MenusContext())
{
Console.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);
//这里插入成功
int records = context.SaveChanges();
Console.WriteLine($"{records} records added");
int hightestCardId = context.MenuCards.Max(c => c.MenuCardId);
var mInvalid = new Menu {
MenuCardId = ++hightestCardId, Text = "invalid", Price = 999.99m
};
context.Menus.Add(mInvalid);
//插入失败
records = context.SaveChanges();
Console.WriteLine($"{records} records added");
}
}
catch (DbUpdateException ex)
{
Console.WriteLine($"{ex.Message}");
Console.WriteLine($"{ex?.InnerException.Message}");
}
Console.WriteLine();
}
public static void Setup()
{
using (var context = new MenusContext())
{
bool deleted = context.Database.EnsureDeleted();
string deletedText = deleted ? "deleted" : "does not exist";
Console.WriteLine($"database {deletedText}");
bool created = context.Database.EnsureCreated();
string createdText = created ? "created" : "already exists";
Console.WriteLine($"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 = context.SaveChanges();
Console.WriteLine($"{records} records added");
}
}
private static void AddTwoRecordsWithOneTx()
{
Console.WriteLine(nameof(AddTwoRecordsWithOneTx));
try
{
using (var context = new MenusContext())
{
var card = context.MenuCards.First();
var m1 = new Menu {
MenuCardId = card.MenuCardId, Text = "added", Price = 99.99m
};
int hightestCardId = context.MenuCards.Max(c => c.MenuCardId);
var mInvalid = new Menu {
MenuCardId = ++hightestCardId, Text = "invalid", Price = 999.99m
};
context.Menus.AddRange(m1, mInvalid);
Console.WriteLine("trying to add one invalid record to the database, this should fail...");
//同一个savechanges,所有操作只要报错会回滚
int records = context.SaveChanges();
Console.WriteLine($"{records} records added");
}
}
catch (DbUpdateException ex)
{
Console.WriteLine($"{ex.Message}");
Console.WriteLine($"{ex?.InnerException.Message}");
}
Console.WriteLine();
}
private static void TwoSaveChangesWithOneTx()
{
Console.WriteLine(nameof(TwoSaveChangesWithOneTx));
//使用IDContextTransaction开启事务
IDbContextTransaction tx = null;
try
{
using (var context = new MenusContext())
//context.Database.BeginTransaction()返回一个IDbContextTransaction的事务
//BeginTransaction这里可以提供隔离级别
using (tx = context.Database.BeginTransaction())
{
Console.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 = context.SaveChanges();
Console.WriteLine($"{records} records added");
int hightestCardId = context.MenuCards.Max(c => c.MenuCardId);
var mInvalid = new Menu {
MenuCardId = ++hightestCardId, Text = "invalid", Price = 999.99m
};
context.Menus.Add(mInvalid);
records = context.SaveChanges();
Console.WriteLine($"{records} records added");
//使用Commit()提交，即使多个SaveChanges()，如果有失败，也会不会提交
tx.Commit();
}
}
catch (DbUpdateException ex)
{
Console.WriteLine($"{ex.Message}");
Console.WriteLine($"{ex?.InnerException.Message}");
Console.WriteLine("rolling back...");
tx.Rollback();
}
Console.WriteLine();
}