services.AddShovel to accept transform method injection

[althunibat]

passing transform method lacks dependency injection, shovel class may have dependencies to be injected to enrich the transformed events.

[alexeyzimarev]

Good point. The issue, as always, is to be able to distinguish between those services, as each shovel (will be called a Gateway in the next version) might need a different one. If you look at the current subscription builder and all the stuff related to registrations of subscriptions, you'll see how cumbersome it becomes...

Still, if we agree that the first working solution would be ok assuming only one shovel needs to be there in one application, I can enable registering a shovel without providing a function.

So, instead of:

services.AddShovel<AllStreamSubscription, AllStreamSubscriptionOptions, EventStoreProducer>("myShovel", x => {...});

You could do this:

services.AddSingleton<MyTransformer>();
services.AddSingleton<RouteAndTransform>(sp => sp.GetRequiredService<MyTransformer>.Transform);
services.AddShovel<AllStreamSubscription, AllStreamSubscriptionOptions, EventStoreProducer>("myShovel");

That can be done quickly.

[althunibat]

we can decide on shovel transform instance upon declaring it, this way it is not one instance which implements RouteAndTransform

services.AddSingleton<MyTransformer>();
services
    .AddShovel<AllStreamSubscription, AllStreamSubscriptionOptions, EventStoreProducer>(
        "IntegrationSubscription",
        sp=>sp.GetRequiredService<MyTransformer>.Transform
    );

[alexeyzimarev]

True, so, basically, for the registration a simple improvement would to accept a function to resolve the transformer.