如何在Entity Framework中回滚事务

Question

string[] usersToAdd = new string[] { "asd", "asdert", "gasdff6" };
using (Entities context = new Entities())
{
    foreach (string user in usersToAdd)
    {
        context.AddToUsers(new User { Name = user });
    }
    try
    {
        context.SaveChanges(); //Exception thrown: user 'gasdff6' already exist.
    }
    catch (Exception e)
    {
        //Roll back all changes including the two previous users.
    }

或者这可能是自动完成的,这意味着如果发生错误,则会针对所有更改取消提交更改.是吗？

Answer 1

好

我创建了一个示例应用程序,例如问题中的示例,然后我在数据库中检查并且没有添加任何用户.

结论:ObjectContext.SaveChange它自动成为一个事务.

注意:我相信如果执行sprocs等将需要事务.

Answer 2

我相信(但我不是EF的专家),在调用context.SaveChanges之前,事务没有开始.我希望该调用的异常会自动回滚它启动的任何事务.替代方案(如果你想控制交易)[来自J.Lerman的"编程实体框架" O'Reilly,pg.618]

using (var transaction = new System.Transactions.TransactionScope())
{
  try
  {
    context.SaveChanges();
    transaction.Complete();
    context.AcceptAllChanges();
  }
  catch(OptimisticConcurrencyException e)
  {
    //Handle the exception
    context.SaveChanges();
  }
}

要么

bool saved = false;
using (var transaction = new System.Transactions.TransactionScope())
{
  try
  {
    context.SaveChanges();
    saved = true;
  }
  catch(OptimisticConcurrencyException e)
  {
    //Handle the exception
    context.SaveChanges();
  }
  finally
  {
    if(saved)
    {
      transaction.Complete();
      context.AcceptAllChanges();
    }
  }

}