Dis-allow nil confirmations.

[steveklabnik]

It doesn't make sense that if we don't confirm, we allow things
to be saved.

I'm submitting this as a PR because there is one test that implies this behavior was expected, so I'm curious if this was an oversight or if this is expected behavior.

[steveklabnik]

Apparently @josevalim has something to say about this.

[josevalim]

This behavior is intentional. The goal of validations is too confirm user
input. A form will always send a blank value if the field is there, so the
validation is triggered.

Now, on console and apis, you don't need to set the field, exactly because
it accepts nil.

Therefore this is a feature, there is a post on plataformatec blog, but I'm
on my phone, so you will have to google it. :)

This topic comes once in a while, it would be worthy to add it to the
documentation. If you want to really not accept nil, add a presence check.

José Valim
www.plataformatec.com.br
Skype: jv.ptec
Founder and Lead Developer

[steveklabnik]

I will add some documentation, I think this behavior is pretty terrible, but if that's the way it is, that's the way it is.

[tonycoco]

Agreed. This is a botched way to handle nils from a form submission. Maybe there's a better solution to pop those nils out of the form's resource params instead?