implementationFactory for Open Generics

[prasannapattam]

I am looking to use a Factory to create the generic object. I want the generic object type passed on to the implementation factory so that I can create the object based on the generic type.

services.AddTransient(typeof(ServiceDocument<>),
    // I need to get the closed generic type here so that the corresponding object is created, i.e., ServiceDocument<Employee>
    p => new ServiceDocument<Employee>()
);

As you see in the above code, in the implementationFactory function, I want to create the object based on the generic type, for example:

- For ServiceDocument<Employee>, I need to create the ServiceDocument<Employee>
- For ServiceDocument<Department>, I have to create the ServiceDocument<Department> object

Is there a way the DI can pass in the object type to this factory function?

[davidfowl]

There's no way to access this today. Is there any way you can avoid using a factory? Or just use a closed generic.

[prasannapattam]

I can do a workaround with constructor.

I recommend enhancing the factory to support this functionality. I see this is a good feature.

[davidfowl]

@prasannapattam The biggest problem is understanding of other containers can flow this context to their factory implementations.

[prasannapattam]

I can see this is a problem on making this work for other containers.

Is it possible to create an overload which works for the default DI. Something like

Func<IServiceProvider, Type, object> implementationFactory

[khellang]

I think I've asked for this before (but maybe not filed and issue) in order to support decoration of open generics, so consider this my 👍

[davidfowl]

@khellang @prasannapattam

I think I've asked for this before (but maybe not filed and issue) in order to support decoration of open generics, so consider this my 👍

Are you willing to do the research to see if all existing container adapters support this?

[seesharper]

I really don't see how this can be supported without doing MakeGenericType somewhere in the factory implementation. That would not be all that efficient

[Eilon]

Closing because we are not planning on adding this feature to the default DI container.