[f8o]

Most of the time I don't need automatic mappers, but it's nice to have good, fast tools available.

When I'm building something in a more domain-driven approach, which I usually strive for, tools for domain model<->dto mapping (assuming the separation between application and domain layers) does not make much sense. Because even when I have a domain model/dto pair with almost the same attributes I will be creating the model via a well named factory method in the domain layer, with notification style validation. And for changes, even for HTTP PUT, specially for HTTP PATCH, I'll be updating a subset of the attributes and for that I'll be using proper entity methods with, again, notification style validation. On both cases manual handling is the way to go.

If you're mapping lots of open fields to your domain models... it's not domain driven. Might be a choice, but should be conscious.

And if a) automatic mapping makes sense for a subset of the application, be it for api dtos or internal matters (you might be dealing with dtos internally for some integrations), and b) we'll really will have a one liner (including a one liner config) instead of mapping N attributes in multiple situations, ok, but I'll consider to define some sort of simpler Mapper interface and put the tool behind it without leaking its details for application and domain layers.