Validations :allow_empty feature

rubyonrails-core
1

So, here's a case something didn't work as expected, and I'm wondering if a feature tweak is worth considering.

If I use :allow_nil => TRUE, validation rules still complain if a form field is submitted empty (w/o using a presence_of rule).

So...

   validates_format_of :first_name, :with => Is_human_name,       :allow_nil => TRUE, :message => Is_not_human_name_msg

Will complain if the field is submitted as empty. Now, empty doesn't conform to the regex I am using, but I was expecting that :allow_nil will cause the validation to be ignored when the value is empty.

After thinking about it, I can see that params creates emptry strings which are not interpreted as nil for saving. That makes sense, and therefore I can see why Rails still validated my format rule.

Ultimately what I was trying to do was have certain messages override the need for others.

If I have this:

   validates_presence_of :first_name

   validates_format_of :first_name, :with => Is_human_name,       :allow_nil => TRUE, :message => Is_not_human_name_msg

And the field is submitted as empty, then the only error message I need to see is the one that says the field cannot be empty. I do not need to see the format_of error message, or another any subsequent rule failure that might apply.

It was suggested that using an :if is the typical strategy for accomplishing that:

   :if => Proc.new { |model_name| model_name.first_name.length > 0 }

That seems rather bulky (especially when repetitive), and I wonder if an :allow_empty => TRUE couldn't be used to provide the behavior I was expecting -- rules are ignored for *empty* fields, not just Nil ones.

Or perhaps it is better named, :ignore_empty => TRUE

Maybe this is too small a use case, but it sure reduces the :if bulk. Just a thought...

2

:allow_blank is in 2.0 AFAIK, so that should do what you want

3

Andrew Kaspick wrote:

:allow_blank is in 2.0 AFAIK, so that should do what you want

Ah. Yep. a search for allow_blank reveals http://dev.rubyonrails.org/ticket/7383

Didn't catch that with my other searches.

4

If I use :allow_blank => false I expect that no blanks are allowed, however, they are allowed.

def test_validates_length_of_with_no_allow_blank

Topic.validates_length_of( :title, :maximum => 5,

:allow_blank=>false )

assert !Topic.create("title" => "abcdefg").valid?

assert !Topic.create("title" => "").valid?

assert !Topic.create("title" => nil).valid?

assert Topic.create("title" => "abcde").valid?

end

This test fails on the 2nd assert.

The default validation options include :allow_nil=>false and :allow_blank=>false. I suggest those are removed, and only when those options are explicitely passed into the options hash of one of the validate methods would you check for allow_nil and/or allow_blank.

Futhermore, now that we have the :allow_blank option, does anyone understand why validate_presence_of can’t use validates_each? And why does that method need to be able to deal with “nonexistent attributes” and all the other validate methods not ??

Cheers

Lawrence