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gnunix

2008-Oct-21 16:58 UTC

Cleaner way to build a "one or the other" validation?

I have an object called dealer.  Dealer has two fields dealer_number
and sub_dealer_number.  It must have 1 OR the other... but not both.
To validate this I have:

class Dealer < ActiveRecord::Base
  validate :dealer_id?

private
  def dealer_id?
    if number.blank? && sub_number.blank?
      errors.add_to_base("You must specify either a Dealer Number OR a
Sub Dealer Number.")
    elsif (number.length > 0) && (sub_number.length > 0)
        errors.add_to_base("You must specify either a Dealer Number OR
a Sub Dealer Number.")
    end
  end
end

This looks really messy to me.  Is there a better way?  Thank you for
your thoughts.

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Frederick Cheung

2008-Oct-22 05:48 UTC

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Re: Cleaner way to build a "one or the other" validation?

On 21 Oct 2008, at 12:58, gnunix wrote:
>
> I have an object called dealer.  Dealer has two fields dealer_number
> and sub_dealer_number.  It must have 1 OR the other... but not both.
> To validate this I have:
>Use the Xor operator ( ^ ) ?

Fred> class Dealer < ActiveRecord::Base
>  validate :dealer_id?
>
> private
>  def dealer_id?
>    if number.blank? && sub_number.blank?
>      errors.add_to_base("You must specify either a Dealer Number OR a
> Sub Dealer Number.")
>    elsif (number.length > 0) && (sub_number.length > 0)
>        errors.add_to_base("You must specify either a Dealer Number OR
> a Sub Dealer Number.")
>    end
>  end
> end
>
> This looks really messy to me.  Is there a better way?  Thank you for
> your thoughts.
>
> >

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Pardee, Roy

2008-Oct-22 15:14 UTC

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Re: Cleaner way to build a "one or the other" validation?

How about:

def validate_dealer_id
  if number.blank? then
    errors.add_to_base("You must specify either a Dealer Number OR a Sub
Dealer Number.") if subnumber.blank?
  else
    erros.add_to_base("A dealer can''t have both a dealer number
AND a sub dealer number") unless subnumber.blank?
  end
end

?

Extra bonus kibbitzing:
 - Would it make things any easier to store both those
   numbers in a single field, and keep track of whether
   a given dealer is a dealer or a sub in a separate
''dealer_type''
   field?
 - FWIW--the ruby convention is that methods whose names
   end in a ? return a boolean.

Cheers,

-Roy

-----Original Message-----
From: rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
[mailto:rubyonrails-talk@googlegroups.com] On Behalf Of gnunix
Sent: Tuesday, October 21, 2008 9:58 AM
To: Ruby on Rails: Talk
Subject: [Rails] Cleaner way to build a "one or the other" validation?


I have an object called dealer.  Dealer has two fields dealer_number and
sub_dealer_number.  It must have 1 OR the other... but not both.
To validate this I have:

class Dealer < ActiveRecord::Base
  validate :dealer_id?

private
  def dealer_id?
    if number.blank? && sub_number.blank?
      errors.add_to_base("You must specify either a Dealer Number OR a Sub
Dealer Number.")
    elsif (number.length > 0) && (sub_number.length > 0)
        errors.add_to_base("You must specify either a Dealer Number OR a
Sub Dealer Number.")
    end
  end
end

This looks really messy to me.  Is there a better way?  Thank you for your
thoughts.



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Michael Kahle

2008-Oct-22 21:41 UTC

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Re: Cleaner way to build a "one or the other" validation?

Frederick Cheung wrote:> Use the Xor operator ( ^ ) ?
> 
> Fred
Sexy.  Thanks.

I changed above to:

class Dealer < ActiveRecord::Base
  validate :dealer_id?

private
  def dealer_id?
    if !(number.blank? ^ sub_number.blank?)
      errors.add_to_base("You must specify either a Dealer Number OR a 
Sub Dealer Number.")
    end
  end
end

Makes me feel less dirty.
-- 
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Michael Kahle

2008-Oct-22 21:43 UTC

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Re: Cleaner way to build a "one or the other" validation?

Roy Pardee wrote:> How about:
> 
> def validate_dealer_id
>   if number.blank? then
>     errors.add_to_base("You must specify either a Dealer Number OR a
Sub
> Dealer Number.") if subnumber.blank?
>   else
>     erros.add_to_base("A dealer can''t have both a dealer
number AND a
> sub dealer number") unless subnumber.blank?
>   end
> end
> 
> ?
> 
> Extra bonus kibbitzing:
>  - Would it make things any easier to store both those
>    numbers in a single field, and keep track of whether
>    a given dealer is a dealer or a sub in a separate
''dealer_type''
>    field?
>  - FWIW--the ruby convention is that methods whose names
>    end in a ? return a boolean.
> 
> Cheers,
> 
> -Roy
I don''t think that your above example is any cleaner then my original 
solution.  However, your bonus kibbitzing (lol) I think is a really good 
thought.  I am going to implement this logic on a later iteration. 
Thanks for this.
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Phillip Koebbe

2008-Oct-23 02:19 UTC

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Re: Cleaner way to build a "one or the other" validation?

Michael Kahle wrote:
> I don''t think that your above example is any cleaner then my
original
> solution.  However, your bonus kibbitzing (lol) I think is a really good 
> thought.  I am going to implement this logic on a later iteration. 
> Thanks for this.
Hi Michael,

For future reference, I needed to do something similar a few months ago 
and ended up creating a custom validation. I wrote about it if you want 
to look into it:

http://per-snicket-y.blogspot.com/2008/04/custom-validations-in-rails-202.html

Peace.
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Rails - Oct 2008 - Cleaner way to build a "one or the other" validation?

Cleaner way to build a "one or the other" validation?

Re: Cleaner way to build a "one or the other" validation?

Re: Cleaner way to build a "one or the other" validation?

Re: Cleaner way to build a "one or the other" validation?

Re: Cleaner way to build a "one or the other" validation?

Re: Cleaner way to build a "one or the other" validation?