EF Code First DBContext and Transactions

Question

I would like know what is the best possible way to implement transactions with DBContext. In particular,

1. Does DbContext.SaveChanges implement transaction internall if i change multiple entities?
2. If i want to call DbContext.SaveChanges multiple times(same contxet/different contxets), how transaction can be achieved?

Colin

Answer 1

1. Yes. SaveChanges uses transaction internally.
2. Use TransactionScope to wrap multiple calls to SaveChanges

Example:

using(var scope = new TransactionScope(TransactionScopeOption.Required,
    new TransactionOptions { IsolationLevel = IsolationLevel.ReadCommitted }))
{
    // Do something 
    context.SaveChanges();
    // Do something else
    context.SaveChanges();

    scope.Complete();
}

Snuff

Be sure to be using Sql 2008 or later as the database (or have the MSDTC service running on the client). Previous versions will escalate the transaction to a distributed transaction on the second SaveChanges. This is due to how DbContext internally handles the opening and closing of its connection. – Sines

Is is possible to get an identity from the first save changes? I always see Id = 0. – Mendes

@Mendes - I think your issue is because of the IsolationLevel settings. Lowering it might help... – Baresark

This wont work with EF 4.3.1. We will have to open the connection on the Objectcontext explicitly before we call context.SaveChanges(). – Disposal

@renegadeMind: Of course this will work with DbContext. What you describe is advanced way used when you want to avoid distributed transaction. – Snuff

@LadislavMrnka Yes you are correct; but don't we want to avoid DTC by default? I assumed that we do and hence my answer! – Disposal

Answer 2

For asynchronous operation do the following.

using(var scope = new TransactionScope(TransactionScopeAsyncFlowOption.Enabled))
{
    // Do something 
    await context.SaveChangesAsync();
    // Do something else
    await context.SaveChangesAsync();

    scope.Complete();
}

References: learn.microsoft.com/en-us/ef/ef6/saving/transactions

Lancelle