Custom Validation for format

Question

I have a class Links. The class has these attributes

1. Twitter
2. Facebook
3. Pinterest
4. Quora

I want to write a validation that makes sure when a user inserts a link into a textbox it starts with http or https.

The validation works, but I have a an issue when the user does not insert a link at all. It still tries to run the validation on the empty attribute and raises the error. The below code is my attempt at checking for a empty attribute.

Here's my validation:

     class Links <  ActiveRecord::Base
     attr_accessible :facebook, :twitter, :quora, :pinterest

     validate :formatted_link

     def formatted_link
      links = %w(facebook twitter pinterest quora)
       if links.any? {|link| self[link].nil?}
         #Don't want it to do any validation if column is nil. 
         #Would like to drop column if user doesn't add a link.
       else
          validates_format_of links, :with => URI::regexp(%w(http https))
          errors.add(:base, "Your link must start with http or https.")
       end
    end

Reason:

If a user just submits "www.twitter.com/username" the url get's appended to my sites url "mydomain.com/page/www.twitter.com/username. Not sure why this is happening. If there is something else I could do to prevent this or something I am missing please let me know.

Thanks.

Answer 1

I think you're trying to do conditional validation in a roundabout way. Since you really just want to allow blanks, you can do it this way:

class Link < ActiveRecord::Base
  Networks = [:facebook, :twitter, :quora, :pinterest]
  attr_accessible *Networks

  validates_format_of *Networks, :with => URI::regexp(%w(http https)), :allow_blank => true
end

Answer 2

I think you need to convert links to a symbol before passing it to validates_format_of, but since it seems to be working for you, I may be wrong or your sample code above may be missing that detail.

Either way, you can skip validation on blanks with:

validates_format_of :foo, with: some_format, allow_blank: true