Querying inside handler of event fired by changes API retrieve outdated data.
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Ivan Montilla
Jun 6, 2020, 5:57:30 PM6/6/20
to RavenDB - 2nd generation document database
I have a hosted service with this Start method:
And this is my Schedule method:
As you can see, when a change is done in CronEntity collection, the Schedule method is called, in this method, a readonly (no tracking) session is created and perform a query over CronEntity.
public async Task StartAsync(CancellationToken cancellationToken) { _logger.LogInformation("Cron scheduler started.");
await ScheduleAsync(cancellationToken); _store.Changes() .ForDocumentsInCollection<CronEntity>() .Subscribe(async _ => await ScheduleAsync(cancellationToken)); }And this is my Schedule method:
private async Task ScheduleAsync(CancellationToken cancellationToken) { _logger.LogInformation("Scheduling cron jobs...");
// [Irrevelant code]
using var session = _store.OpenAsyncSession(new SessionOptions { NoCaching = true, NoTracking = true }); var jobs = await session.Query<CronEntity>() .Where(x => x.IsActive) .Select(x => new { x.Expression, x.Parameters, x.Type }) .ToArrayAsync();
// [Irrevelant code] }As you can see, when a change is done in CronEntity collection, the Schedule method is called, in this method, a readonly (no tracking) session is created and perform a query over CronEntity.
My problem is when I perform the query, I get the data how was before the last change that fire the changes API. I tried oppening the session with tracking and caching disabled, but my data does't reflect the last changed.
Any idea?
Ivan Montilla
Jun 6, 2020, 6:11:18 PM6/6/20
to RavenDB - 2nd generation document database
I tried with await Task.Delay(1000) before creating the session and now data is syncronized.
await Task.Delay(1000); // https://groups.google.com/forum/#!topic/ravendb/sY4sTSOahHs using var session = _store.OpenAsyncSession(new SessionOptions { NoCaching = true, NoTracking = true }); var jobs = await session.Query<CronEntity>() .Where(x => x.IsActive) .Select(x => new { x.Expression, x.Parameters, x.Type }) .ToArrayAsync();I think this is because the changes API is fired when started to save and not after saving. Is this correct? How can I handle it?
Egor Shamanaev
Jun 7, 2020, 3:25:50 AM6/7/20
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Hi,
Yes, Subscribe hit each time you do a change to the tracked entity in session, for example
session.Store(new Employee(), "employees/1");
session.SaveChanges();
the Subscribe will be executed, after session.Store(), in your ScheduleAsync() method you make a query to the server but the actual change is not yet sent/processed by the server.
You can take a look on OnAfterSaveChanges event: https://ravendb.net/docs/article-page/4.2/Csharp/client-api/session/how-to/subscribe-to-events#onaftersavechanges this will make sure that the server already processed the changes.
Yes, Subscribe hit each time you do a change to the tracked entity in session, for example
session.Store(new Employee(), "employees/1");
session.SaveChanges();
the Subscribe will be executed, after session.Store(), in your ScheduleAsync() method you make a query to the server but the actual change is not yet sent/processed by the server.
You can take a look on OnAfterSaveChanges event: https://ravendb.net/docs/article-page/4.2/Csharp/client-api/session/how-to/subscribe-to-events#onaftersavechanges this will make sure that the server already processed the changes.
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 | Egor Developer / Hibernating Rhinos LTD
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Oren Eini (Ayende Rahien)
Jun 7, 2020, 6:58:35 AM6/7/20
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I think that you'll need to use WaitForNonStaleResults() (and pass the relevant change vector there) in the Suscribe call.
You are getting notified before the indexes had a chance to run
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| Oren Eini CEO / Hibernating Rhinos LTD
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Ivan Montilla
Jun 7, 2020, 8:29:28 AM6/7/20
to RavenDB - 2nd generation document database
Hi Egor, that no was my problem because I made the changes in the studio to fire the subscription.
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Ivan Montilla
Jun 7, 2020, 8:30:38 AM6/7/20
to RavenDB - 2nd generation document database
Hi Oren. Thank you! I added WaitForNonStale in the query and now is working as I expected.
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Egor
Developer / Hibernating Rhinos LTD
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