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IEnumerable<Scoped<T>> doesn't work as expected #230
Description
Let's say your container contains many IFrob exports, let's call them Frob1 and Frob2.
If you want all of them you can Locate<IEnumerable<IFrob>>(), which will give you Frob1, Frob2.
Maybe you want to be able to spawn new frobs and locating IEnumerable<Func<IFrob>> does give you two factories. If you .Select(f => f()) then you end up with Frob1, Frob2, as expected.
Now let's say that in addition to that you want each factory to resolve in a new scope. You locate IEnumerable<Func<Scoped<IFrob>>> which returns 2 factories as expected. But (ignoring Dispose for now) if you look at .Select(f => f().Instance) then you'll notice every scoped instance resolves to the same IFrob: Frob2, Frob2 (based on priority, etc.)
It seems to me that Scoped "forgets" what specific IFrob it was supposed to be and just performs a plain Locate<IFrob> again, which is not what I want.
This makes Scoped<IFrob> useless/incompatible with IEnumerable. In fact, just locating IEnumerable<Scoped<IFrob>> returns Frob2, Frob2.
This is a simplified test case. My full code was:
IEnumerable<Meta<Func<string, Scoped<T>>>>
because on top of that I wanted per-IFrob meta information (before invoking the factory; meta infos seem to be right) and named scopes (seems to work ok as well).
Activity
[-]IEnumerable<Func<Scoped<T>>> doesn't work as expected[/-][+]IEnumerable<Scoped<T>> doesn't work as expected[/+]ipjohnson commentedon Jul 25, 2019
I see what you mean it's really not a robust implementation. I'll need to think about it a bit to see what's the best solution for this.
jods4 commentedon Jul 25, 2019
Can you advise a workaround in the meantime? I'm having a hard time figuring out how to do this any other way.
I want to be able:
IFrob, especially their metadata.IFrobon demand, in their own scope.ipjohnson commentedon Jul 31, 2019
Sorry meant to reply this weekend. There isn't a good work around for the moment but I do think I should be able to find some time this weekend to fix it properly and do a beta release.
jods4 commentedon Jul 31, 2019
Thanks.
FWIW I managed to workaround the problem but it's very convoluted.
I used named exports instead metadata; then i'm casting the
IExportLocatorScopetoDependencyInjectionContainerso that I can useStrategyCollectionContainer.GetActivationStrategyCollectionto enumerate all keys and metadata related to an interface; finally I can create a lifetime scope andLocatethe interface and key previously gathered to find the instance that I want.It's ugly :(
but it works for now.
fixing scoped implementation for issue #230
ipjohnson commentedon Aug 5, 2019
I have one more issue I need to address before I can do a beta release but you can test the fix in the nightly nuget feed
https://ci.appveyor.com/nuget/grace-master
jods4 commentedon Aug 5, 2019
Thanks!
Switching feeds is a bit complicated (don't ask) but if you do a prerelease on Nuget I can test.
Otherwise I can wait a little bit more.
fixing problem with wrappers for issue #230
ipjohnson commentedon Aug 11, 2019
I've released a new version 7.1.0-beta
jods4 commentedon Aug 12, 2019
Thanks, I referenced the 7.1 beta and it works now! ❤️