I have a set of generic classes that are utilized in typed controllers in the following way:

public class RootController<TIndexType, TEntityType> : ControllerBase
{
    private readonly IDataFetcher<TEntityType> _dataFetcher;
    private readonly IIndexPopulator<TIndexType> _indexPopulator;
    private readonly IMapper _mapper;
    public RootController(
        IIndexPopulator<TIndexType> indexPopulator,
        IDataFetcher<TEntityType> dataFetcher,
        IMapper mapper)
    {  
        _indexPopulator = indexPopulator;
        _dataFetcher = dataFetcher;
        _mapper = mapper;
    }
}

There are about 15 controllers extending this generic controller with specific types, ie
public class DomainController: RootController<DomainIndex, DomainItem>

Typed versions of IDatFetcher and IIndexPopulator have not been created, as typed instantiation is handled by the DI container.

The issue: I have a hosted BackgroundService that is kicked off at Startup that handles async configuration for the service. As part of this, I need to iterate over all entity types, utilizing IDataFetcher.GetItems to get IEntityType items, map those items to the associated TIndex type, and then pass the mapped TIndex items to IIndexPopulator.PopulateAsync.

I see 3 possible solutions, each with significant drawbacks:

1. Create methods to handle data fetching and index population generically based on a list of index types.
   • Drawback: I’ve been working through getting this code written and it’s quite complex, plus I’m concerned about performance and maintainability as it requires the extensive use of reflection and/or dynamics.
2. Call the associated endpoint in the typed controllers. RootController provides a “/{indexName}/seed” endpoint that covers the needed functionality.
   • Drawback: it seems hacky to make an http call to outside the service in order to hit functionality in the service
3. Create typed versions of all IDataFetcher and IIndexPopulator classes.
   • Drawback: This is a lot of code to write and maintain, any time a new index type is created, the BackgroundService will have to be modified.

Is there another approach I’m missing?