C#•13mo ago

✅ Urgent | Cannot update property in EF because another instance with the same key is being tracked

Hi, so I have following code: Basically I get a batch to update the field

var batch = await context.Batch.FirstOrDefaultAsync(b => b.BatchId == id);
if (batch == null) throw new BatchNotFoundException($"No batch found with id {id}");
context.Entry(batch).Property(b => b.Status).IsModified = true;
batch.Status = status;

var batch = await context.Batch.FirstOrDefaultAsync(b => b.BatchId == id);
if (batch == null) throw new BatchNotFoundException($"No batch found with id {id}");
context.Entry(batch).Property(b => b.Status).IsModified = true;
batch.Status = status;

I get the error on the 'entry' line. If I leave it, it doesn't update the field (yes I do commit later on in my CQRS). I have a code freeze tomorrow night so henc ethe Urgency as It's an imprtant feature the client wants which they only let us know very late... Full error

The instance of entity type 'Batch' cannot be tracked because another instance with the same key value for {'BatchId'} is already being tracked. When attaching existing entities, ensure that only one entity instance with a given key value is attached. Consider using 'DbContextOptionsBuilder.EnableSensitiveDataLogging' to see the conflicting key values.

The instance of entity type 'Batch' cannot be tracked because another instance with the same key value for {'BatchId'} is already being tracked. When attaching existing entities, ensure that only one entity instance with a given key value is attached. Consider using 'DbContextOptionsBuilder.EnableSensitiveDataLogging' to see the conflicting key values.

26 Replies

Angius•13mo ago

Any reason you're updating this way? Usually it's

var thing = await ctx.Things.FirstOrDefaultAsync(...);
thing.Prop = newValue;
await ctx.SaveChangesAsync();

var thing = await ctx.Things.FirstOrDefaultAsync(...);
thing.Prop = newValue;
await ctx.SaveChangesAsync();

or better yet,

var rows = await ctx.Things
    .Where(...)
    .ExecuteUpdateAsync(e => e.SetProperty(t => t.Prop, newValue);

var rows = await ctx.Things
    .Where(...)
    .ExecuteUpdateAsync(e => e.SetProperty(t => t.Prop, newValue);

Also, the only time when I was ever met with this error, is when something fucky-wucky happened with asynchronous code So some async void method, an unawaited task, or other stuff like that

TempticaOP•13mo ago

never heared of the second one, will give that a shot, but the first one did not work as the value didn't get updated

Angius•13mo ago

What type is batch.Status?

TempticaOP•13mo ago

Enum

Angius•13mo ago

And the db you're using?

TempticaOP•13mo ago

SQL Server never had problems with the Enum before though in case you're wondering

Angius•13mo ago

Yeah, it should work I'm asking because NpgSQL had issues tracking array columns for example, so thought it might be similar But an enum is straightforward

TempticaOP•13mo ago

Okay that was stupidly easy and I somehow never came across this solution on the internet, Even AI didn't suggest it. I don't understand how people trust AI soo much with their code but oh well, you're a legend for helping me out

Angius•13mo ago

What was the issue?

TempticaOP•13mo ago

ExecuteUpdateAsync worked fine

Angius•13mo ago

Nice

TempticaOP•13mo ago

but anything else I tried had tracking issues or just didn't update at all

Angius•13mo ago

I'd still check the project for wonky async code This worked because it does the update in a single query As opposed to fetching the entity and then saving it

TempticaOP•13mo ago

it's all async so yeah

Angius•13mo ago

When it's two separate queries, something can creep into the middle Especially with some stray async void controller somewhere Etc

TempticaOP•13mo ago

foreach (var b in request.Notification.ChangedBatches) { await _uow.BatchRepository.UpdateBatchStatus(b.BatchId, Status.AwaitConfirmation); } I do await it, I did use async task etc so yeah, no clue

Angius•13mo ago

Yeah, this is fine But it could be async code anywhere else I'd at least run a cursory solution-wide search for async void

TempticaOP•13mo ago

which groupmate broke my code sus

😄 The frontend does have it but that shouldn't really be it right?

Angius•13mo ago

Should have no impact on the backend, yeah

TempticaOP•13mo ago

yeah backend does not have any async voids

Angius•13mo ago

Oh well, that's not it, then If it works it works though, that's what matters lol

TempticaOP•13mo ago

Exactly! and it saves me some lines of code, also a +

Angius•13mo ago

Yep, the .Execute...() methods are probably my favourite addition to EF Core

TempticaOP•13mo ago

I really never saw them before. But imagine school actually explaining some USEFULL stuff 😄 altho I didn't see it while doing research so that's also on me

Angius•13mo ago

They're fairly new, fwiw EF Core 7 or thereabouts

TempticaOP•13mo ago

okay fair enough, this is teh first year we're allowed to use .NET 7 even before they kept using .net 5 anyways, thank you very much again!

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✅ Urgent | Cannot update property in EF because another instance with the same key is being tracked

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