[DotvvmStartup] How to inject custom service into custom ExceptionFilterAttribute class

[MarianV]

Hi,

I have these:

And

And it fails like this:

How can I use my sessionToolbox inside OnCommandExceptionAsync() ?

PS:
I also want to set session entry

[exyi (Standa Lukeš)]

Unfortunately, dependency injection does not work into the DotvvmStartup class, since it can also configure service container itself. You have to explicitly call config.Services.GetRequiredService<SessionToolbox>() to obtain the service you want to pass to the action filter.

[MarianV]

It crashes the app with this:

‘Cannot resolve scoped service ‘NGM.Services.SessionToolbox’ from root provider.’

Am I calling it wrong or missing something? I already tried adding SessionToolbox as transient/scoped/singleton service in Program.cs (.NET 8 web app).

PS:

I can also obtain the service in Program.cs:

[MarianV]

I got it to work.

For some reason (that I don’t understand), apart from the “GetRequiredService” line, I needed to also add services in ConfigureServices() of DotvvmStartup.cs:

[exyi (Standa Lukeš)]

The attribute will be a singleton, so it will break if you service is stateful. I think you should either make the service singleton too, or call GetRequiredService inside the attribute method — then even Scoped should work fine.