I know I said this before, but at some point we need to have a library that handles validation so that all these dances to check the request and its params and error out depending on it is getting the controllers fat and harder to follow. Possible library options here could be WTForms or Validictory (maybe even Notario (notario.cafepais.com).

I think that only one that has support for Pecan directly is WTForms. But Notario would be nicer (I am biased here obviously). The implementation for integrating it with Pecan would be easy. This is how someone attempted support for Validictory: https://github.com/cleverdevil/pecan-validictory