title: Alpha-numeric regex from a ruby on rails 3 app not working in my ruby on rails 4 app
body: <p>This is my model:</p>
  
  <pre><code>class Garment
      include ActiveAttr::Model
      #include ActiveModel::Validations
      extend CarrierWave::Mount
  
      attribute :title
  
      mount_uploader :image, ImageUploader
  
      alpha_numeric_regix = /\A[a-zA-Z0-9-_]\z/
  
  
      validates :title,       :presence      =&gt; true,
                              :length        =&gt; { :minimum =&gt; 5, :maximum =&gt; 30 },
                              :format        =&gt; {
                                                   :with =&gt; alpha_numeric_regix,
                                                   :message =&gt; "must contain letters, dashes and underscores only"
                                                 } 
  </code></pre>
  
  <p>How ever my actual form keeps telling me the validation has failed when I use purely letters and spaces e.g. VA Yellow Top</p>
  
  <p>Rubular: <a href="http://rubular.com/r/ynd3DOWCxe" rel="nofollow">http://rubular.com/r/ynd3DOWCxe</a></p>
  
  <p>What could the problem be. In rubular using two letter "VA" fails validation as well.</p>
  
  <p>What could be going on? </p>