title: Default URL not loading with Carrierwave in Rails
body: <p>I'm having issues setting a default image in my carrierwave uploader. It seems to be appending a weird class to the front of the URL but not rendering the image. See my code below.</p>
  
  <p><strong>Helper</strong></p>
  
  <pre><code> # encoding: utf-8
  
  class UserpicUploader &lt; CarrierWave::Uploader::Base
  
    CarrierWave::SanitizedFile.sanitize_regexp = /[^[:word:]\.\-\+]/
    # Include RMagick or MiniMagick support:
    include CarrierWave::RMagick
    # include CarrierWave::MiniMagick
    # Include the Sprokets helpers for Rails 3.1+ asset pipeline compatibility:
    # include Sprockets::Helpers::RailsHelper
    # include Sprockets::Helpers::IsolatedHelper
  
    # Choose what kind of storage to use for this uploader:
    storage :file
    # storage :fog
  
    # Override the directory where uploaded files will be stored.
    # This is a sensible default for uploaders that are meant to be mounted:
    def store_dir
      "uploads/#{model.class.to_s.underscore}/#{mounted_as}/#{model.id}"
    end
  
  
  
    # Process files as they are uploaded:
  
    version :normal do
     process :resize_to_fill =&gt; [162, 163]
    end
    # Provide a default URL as a default if there hasn't been a file uploaded:
  
       def default_url
       # For Rails 3.1+ asset pipeline compatibility:
         # asset_path("fallback/" + [normal, "profile_default_pic.png"].compact.join('_'))
         "/images/fallback/" + [normal, "profile_default_pic.png"].compact.join('_')
       end
  
    #
    # def scale(width, height)
    #   # do something
    # end
  
    # Create different versions of your uploaded files:
    # version :thumb do
    #   process :scale =&gt; [50, 50]
    # end
  
    # Add a white list of extensions which are allowed to be uploaded.
    # For images you might use something like this:
    def extension_white_list
       %w(jpg jpeg gif png)
    end
  
    # Override the filename of the uploaded files:
    # Avoid using model.id or version_name here, see uploader/store.rb for details.
      def filename 
        if original_filename 
          @name ||= Digest::MD5.hexdigest(File.dirname(current_path))
          "#{@name}.#{file.extension}"
        end
      end
  
  end
  </code></pre>
  
  <p><strong>EDIT...</strong></p>
  
  <p>Here is the edited code that worked. I had to put the image in public/fallback instead of Assets/images/fallback.</p>
  
  <pre><code># encoding: utf-8
  
  class UserpicUploader &lt; CarrierWave::Uploader::Base
  
    CarrierWave::SanitizedFile.sanitize_regexp = /[^[:word:]\.\-\+]/
    # Include RMagick or MiniMagick support:
    include CarrierWave::RMagick
    # include CarrierWave::MiniMagick
    # Include the Sprokets helpers for Rails 3.1+ asset pipeline compatibility:
    include Sprockets::Helpers::RailsHelper
    include Sprockets::Helpers::IsolatedHelper
  
    # Choose what kind of storage to use for this uploader:
    storage :file
    # storage :fog
  
    # Override the directory where uploaded files will be stored.
    # This is a sensible default for uploaders that are meant to be mounted:
    def store_dir
      "uploads/#{model.class.to_s.underscore}/#{mounted_as}/#{model.id}"
    end
  
  
  
    # Process files as they are uploaded:
  
    version :normal do
     process :resize_to_fill =&gt; [162, 163]
    end
    # Provide a default URL as a default if there hasn't been a file uploaded:
  
       def default_url
       # For Rails 3.1+ asset pipeline compatibility:
           asset_path("fallback/" + [normal, "profile_default_pic.png"].compact.join('_'))
         # "/fallback/" + [normal, "profile_default_pic.png"].compact.join('_')
       end
  
    #
    # def scale(width, height)
    #   # do something
    # end
  
    # Create different versions of your uploaded files:
    # version :thumb do
    #   process :scale =&gt; [50, 50]
    # end
  
    # Add a white list of extensions which are allowed to be uploaded.
    # For images you might use something like this:
    def extension_white_list
       %w(jpg jpeg gif png)
    end
  
    # Override the filename of the uploaded files:
    # Avoid using model.id or version_name here, see uploader/store.rb for details.
      def filename 
        if original_filename 
          @name ||= Digest::MD5.hexdigest(File.dirname(current_path))
          "#{@name}.#{file.extension}"
        end
      end
  
  end
  </code></pre>