实体框架6.1中的事务范围回滚

Question

I have a problem with TransactionScope rollback.

When rolling back the TransactionScope state of objects in context (changetracker) changes from add to modify

private xType _x 
{
    get;
    set
}

public void add(x: xtype) 
{
    context.xlist.add(x);
}

public xclass: object 
{
    public xclass() 
    {
        _x = new xtype();
        add(_x);
    }

    public void savechanges; 
    {
        using(transactionscope = new transactionscope()) 
        {
            try 
            {
                context.savechanges();
                x = 0;
                x = x / x;
                transcope.complete();
            } catch 
            {
                transcope.rollback();
            }
        }
    }

Project uses .net 4.0, vs 2013, ef 6.1, SQL Server 2008 Express, and uses UnitOfWork, Repository patterns

Answer 1

You are modifying your objects after having saved them. That makes them modified.

EF does nothing special when a transaction rolls back. None of its internal state changes. Entity objects are not reverted back. The best pattern is to abandon the EF context after a rollback.

You do not need to explicitly rollback. Delete the catch. Right now all that it accomplishes is to swallow all errors.

Answer 2

Please do not use transactionscope this way. Transaction scope is a scope. You should do something with your database withing the using clause where your create the transaction scope. What people do a lot is, after applying changes, commit them on them by calling the commit method. If there is a crash, nothing is committed and transaction scope knows that the changes so far require a rollback. Transaction scope can be used to implement the "unit of work" design pattern. Things within the using clause are considered to be one unit of work. They should be done all (or not at all). Therefore, some kind of rollback is needed when there is a crash before calling commit. Doing things almost completely is not accepted, since it is one unit of work.

Here is some code example that explains the basic concept. https://msdn.microsoft.com/en-us/library/system.transactions.transactionscope(v=vs.110).aspx

Here are more examples: http://www.codeproject.com/Articles/690136/All-About-TransactionScope