I have a GUI like this:

New Persons

I want to allow submit only if the user leaves a row empty or enters values in both text fields of the row.

I have a custom validation function for each field where I check the model (given via parameter) and return a validation item.
My problem is that the custom validation functions are only called when there are values given in the text fields.
If I fill both fields in a row and clear one field, no custom validation function is called after clearing.

How can i do that?

Can you think of optional custom validation for empty fields?

I'm new to github and angular, I hope it's right to create an issue for that.
I tried a lot of angular validation apis those days but your solution matches my requirements best.

Nice solution, thank you very much