RC2 ForEachAsync does not work anymore

[bragma]

Hi,
I've just updated to RC2 and some of my tests are failing. It seems that this sample code using ForEachAsync is not working anymore:

await _dbContext.Stuff.Where(s => s.OtherId== otherId).ForEachAsync(s =>
{
    s.OtherId = defaultId;
});

The exception message is "New transaction is not allowed because there are other threads running in the session." when executing "SaveChangesAsync()"

My workaround at the moment is to materialize the results in a list and then use a foreach:

var listOfStuff = await _dbContext.Stuff.Where(s => s.OtherId== otherId).ToListAsync();
foreach(var s in listOfStuff)
{
    s.OtherId = defaultId;
}

Am I doing something wrong with ForEachAsync?
Thanks!

[divega]

@bragma I am surprised you get this exception since there is no call to SaveChangesAsync() in the code snippet. Is s.OtherId = defaultId really the only thing that is happening inside the ForEachAsync() loop?

On the other hand, if you are actually trying to save inside the loop, you are hitting a known limitation of SQL Server/SqlClient: you cannot create a transaction on a connection while you are still consuming results of a query in the same connection. But in that case, I am surprised you were not hitting this in RC1 as well.

[bragma]

@divega you are right, the snippet was just a part of a slightly larger method and I only hinted to the following SaveChangesAsync (but outside the loop). Still, no other changes were happening in the ForEachAsync(). I've ran the test in the past dozen of times and never had the problem, while it showed immediately when moving to RC2. Here is the complete code:

public async Task DeleteGroup(Group group)
{
    // Get default group for association
    var defaultGroupId = await GetAssociationDefaultGroupId(group.AssociationId);

    // Set all associate's group id to default if they were set to the group we want to delete
    await _dbContext.Associates.Where(a => a.GroupId == group.GroupId).ForEachAsync(a =>
    {
        a.GroupId = defaultGroupId;
    });

    _dbContext.Groups.Remove(group);
    await _dbContext.SaveChangesAsync();
}

public async Task<int> GetAssociationDefaultGroupId(int associationId)
{
    return await _dbContext.Groups.OrderBy(g => g.GroupId).Where(g => g.AssociationId == associationId).Select(g => g.GroupId).FirstOrDefaultAsync();
}

"Associate.GroupId" is a foreign key linking each associate with their group. This code worked fine in RC1, i.e. it never caused its tests to fail.

[divega]

@bragma thanks for the additional details. If your code really looks like that I am afraid we could be failing to finish consuming and disposing the query results in ForEachAsync().

cc @anpete

[divega]

@bragma BTW, in case it is relevant, what is in GetAssociationDefaultGroupId()?

[bragma]

@divega I've updated my previous post with the missing method. I don't think its relevant, btw.

[anpete]

@bragma Are you able to re-test this against a nightly build? You can use this feed: https://www.myget.org/F/aspnetvnext/api/v3/index.json

[bragma]

@anpete sure, I'll try to do it as soon as I get some breath from my job :)

[bragma]

@anpete sorry for the long delay, today I had some time to test against build "1.0.0-rc3-21267" and everything went well. My tests passed, I can mark this as fixed.