MSDTC + Linq to Sql Update

When I was writing my previous article, I was keenly aware that it had it's limitations. One in particular was using an already open DataContext.

Take the following code:

// Create outside TransactionScope
var c1 = new UserDataContext();

using (var scope = new TransactionScope())
{
    c1.Users.ToList();

    // This will promote to MSDTC
    using (var c2 = new UserDataContext())
        c2.Users.ToList();

    scope.Complete();
}

Since it was created outside the TransactionScope I have no way of automatically sharing these connections.

To help solve this problem (cleanly) I added a SharedConnectionScope class and a UseExistingConnection call (shown below) - both take an existing DataContext.

// Create outside TransactionScope
var c1 = new UserDataContext();

using (var scope = new TransactionScope())
using (SharedDataContext.UseExistingConnection(c1))
{
    c1.Users.ToList();

    // This will share existing connection
    using (var c2 = new UserDataContext())
        c2.Users.ToList();

    scope.Complete();
}

Caveat: It only works with one 'external' connection, but that's still better than none.

You can grab the updated code here.