Question

Using Carrierwave to upload Images,
I want to write 1 function to handle all my image includes in several sizes.

  image_tag @photo_main.file.url(:img_122x145) rescue nil

The :img_120x120 is defined in Carrierwave uploader but why the :img_120x120 semicolon before its name? In what format is this?

Wanted outcome:

def get_avatar(size)

   image_tag @photo_main.file.url(size) rescue nil

end

How could this be done?

UPDATE 1:

Fails with : ActionView::Template::Error (undefined method `file’ for nil:NilClass):
1: .ruler
2:
3: //= show_avatar_profile(@profile.id)
4: = show_avatar_new(@profile.id, “96×96”)

  def show_avatar_new(id, size)

    puts "size is"
    size =  size.to_sym
    puts size

    @photo_main = Photo.where(:attachable_id => id, :attachable_type => "Profile", :main => true, :moderated => true, :approved => true).first
    @photo = Photo.where(:attachable_id => id, :attachable_type => "Profile", :moderated => true, :approved => true).first

    if @photo_main
      image_tag @photo_main.file.url(size)
    else
      image_tag @photo.file.url(size)
    end

  end

UPDATE 2:

class PhotoUploader < CarrierWave::Uploader::Base

  include CarrierWave::RMagick
  CarrierWave::SanitizedFile.sanitize_regexp = /[^[:word:]\.\-\+]/

  storage :file

  def store_dir
    "uploads/#{model.class.to_s.underscore}/#{mounted_as}/#{model.id}"
  end


  version :img_48x48 do
    process :resize_to_fill => [48, 48]
  end

  version :img_58x58 do
    process :resize_to_fill => [58, 58]
  end

  version :img_75x75 do
    process :resize_to_fill => [75, 75]
  end

  version :img_96x96 do
    process :resize_to_fill => [96, 96]
  end

  # Used in search results,
  version :img_122x145 do
    process :resize_to_fill => [122, 145]
  end

  version :img_200x200 do
    process :resize_to_fill => [200, 200]
  end


  protected

  def secure_token(length=32)
    var = :"@#{mounted_as}_secure_token"
    model.instance_variable_get(var) or model.instance_variable_set(var, SecureRandom.hex(length/2))
  end

  def delete_empty_upstream_dirs
    path = ::File.expand_path(store_dir, root)
    Dir.delete(path) # fails if path not empty dir

    path = ::File.expand_path(base_store_dir, root)
    Dir.delete(path) # fails if path not empty dir
  rescue SystemCallError
    true # nothing, the dir is not empty
  end

end

Answer 1

In Ruby, things beginning with colons : (not semicolons ;!) are symbols, which are essentially immutable strings.

"img_122x145".to_sym # => :img_122x145

It seems like what you’ve written there is exactly what you need. If you’re wondering where to put it, you could put it in a helper

# app/helpers/avatar_helper.rb
def get_avatar(size)
  image_tag @photo_main.file.url(size)
end

Please don’t use rescue nil there, though. What error are you trying to catch? It would be much better to explicitly avoid it rather than using exceptions as flow control.

image_tag @photo_main.file.url(size) if @photo_main.file?

would be sufficient to avoid the problem of a @photo_main without a file, and is much more intention-revealing (and, in fact, more performant). Worst-case, you should still explicitly state what sort of error you’re expecting to get

def get_avatar(size)
  image_tag @photo_main.file.url(size)
rescue SomeSpecificErrorThatCantBeAvoided
  nil
end

This short (<3min) screencast makes an excellent case for avoiding inline rescue.

---

Update

When you create versions in CarrierWave, it creates methods to access them – you don’t pass an argument to url:

@photo.file.img_122x145.url

If you want to get a variable version, though, they are available through versions (a hash):

size = :img_122x145
@photo.file.versions[size].url

That won’t solve your remaining problem, which is simply that your queries aren’t finding anything.