It seems PerchAPI_SubmittedForm::validate() does not handle arrays at the moment. So an input like this always throw an error (given the required attribute is set):
I can workaround this by using an alternative syntax (e.g. email__primary) and writing a little more PHP if I really wanted to have it as an array. However, I can't avoid using arrays for handling multiple file uploads:
It would be very helpful if PerchAPI_SubmittedForm can validate values submitted as arrays.