danielasfregola / data-validation Goto Github PK

#Hi Daniela - I followed solutions from your Scala Exchange talk and this project, and it worked out for me pretty well. That was a really nice approach and a good use of Cats IMO. My question relates to the case in which I have two or more validations per case class member, and I need to combine these validations. It turns out there is no easy way to combine 2 or more ValidatedNel (or similar) objects into one. The provided "combine" method is not ideal, as it combines not only errors (which is desired), but unfortunately also values. I ended up tweaking my value type, having its "combine" method overridden (by forming a semigroup with trivial one-sided combination). Please have a look at examples in project https://github.com/miloszm/scala-validation, there is a little Word document there in the docs folder with pointers to relevant examples. Classes CombineValidator and CombineValidatorImproved and their tests illustrate the gist of the problem.