[orra]

I've used Automapper a few times, in Enterprise software which takes separate layers to a dogmatic extreme. Automapper always felt like a code smell: if the layers are so trivially mappable, should they really be different layers? Alternatively, isn't automapping a violation of the philosophy of separation of layers?

All that said, given these mappers exist, the fact this Mapperly does ahead of time code generation is an advantage over the previous generation of generators which had to use reflection.

[barking_biscuit]

After the number of times I've seen AutoMapper absolutely abused and had to track down some really head-scratching bugs introduced by it, I've come to the conclusion that I'd rather just eat the pain of writing the mappings by hand.

And after the number of times I've started a job and asked about something that looked arcane, odd, and difficult to work with and gotten the reply "well we used to have this code generation tool", I've come to the conclusion that I don't wish to rely on code generation tools either because the incentives to build code generation tools and the incentives to maintain them seem to be severely misaligned such that building on a foundation of code generation tools seems to be equivalent to building on a foundation of quicksand.

[mjburgess]

I assume the automapper is subsetting on the target type's structure, right?

So its something like this,

    target_dto = { k: MyDbModel.get(k) for k in MyTargetModel.keys() }

Writing this is a big issue with simple static languages (ie., those without much compile-time programming).

This deficiency should really be addressed at the language-level. Ie., what you want is structural typing in the view-layer, and a means of restructuring (ie., filtering) the original db object.

So,

    renderView(myDbModel as {Just,The,Necessary,Fields})

I'd imagine with C# Shapes, Extension Methods and Pattern Matching, you'd be able to do roughly this -- but i'm not sure of the status of "shapes" (ie., typeclasses) in the C# RFC process.

[orra]

Thanks for this thoughtout reply. Automapping can also be used for renaming, and simple type conversions.

But yes, structural typing and other interesting typesystems can make this first class.

I didn't realise serious work had been put into typeclasses for C#. Interesting, but unfortunately it seems to have stalled.