But if you intend to save to a model after the form validates, then you can't escape the models' validations:

either you check that the models pass their own validations ahead of time (like I want to do, and I think @mattheworiordan was wanting to do), or you have to accept that one of the following outcomes is possible/inevitable if the models' own validations fail:

1. if you use object.save then it may silently fail to save
2. if you use object.save then it will fail to save and raise an error

Are either of those outcomes acceptable to you? To me, they seem not to be. Hence we must also check for / handle the models' validations. Hence we need a way to aggregate errors from both the form object (context-specific validations) and from the models (unconditional/invariant validations that should always be checked by the model), and present them to the user.

What do you guys find to be the best way to accomplish that?

I am interested to know what best practices you use / still use today after all these years. I keep finding myself running into this same problem/need, which is how I ended up looking for what the current options are for form objects today...