Reload Paperclip file uploads when validation fails

Question

I am new to rails. I am currently setting up Paperclip for a model in Rails 3. When one of form fields fails validation, It fails to reload my uploaded image again.Its asks user to upload newly. It doesn't look user friendly.

I would like to do two things to solve this issue. If all the fields are filled correctly I would like to store it in my app (system folder as usual paperclip does ).If fields fails validation, want to store the image in separate folder temporally until it get saved.

Am I going in right path? Else is there any simple way to do this?

Answer 1

Unfortunately, Paperclip saves the uploaded file only upon a successful save of the model containing the file.

I believe the easiest option is to do the validation client-side with javascript so there is no need for all the back-end configuration/hacking.

Answer 2

I had to fix this on a recent project. It's a bit hacky but it works. I've tried calling cache_images() using after_validation and before_save in the model but it fails on create for some reason that I can't determine so I just call it from the controller instead. Hopefully this saves someone else some time!

model:

class Shop < ActiveRecord::Base    
  attr_accessor :logo_cache

  has_attached_file :logo

  def cache_images
    if logo.staged?
      if invalid?
        FileUtils.cp(logo.queued_for_write[:original].path, logo.path(:original))
        @logo_cache = encrypt(logo.path(:original))
      end
    else
      if @logo_cache.present?
        File.open(decrypt(@logo_cache)) {|f| assign_attributes(logo: f)}
      end
    end
  end

  private

  def decrypt(data)
    return '' unless data.present?
    cipher = build_cipher(:decrypt, 'mypassword')
    cipher.update(Base64.urlsafe_decode64(data).unpack('m')[0]) + cipher.final
  end

  def encrypt(data)
    return '' unless data.present?
    cipher = build_cipher(:encrypt, 'mypassword')
    Base64.urlsafe_encode64([cipher.update(data) + cipher.final].pack('m'))
  end

  def build_cipher(type, password)
    cipher = OpenSSL::Cipher::Cipher.new('DES-EDE3-CBC').send(type)
    cipher.pkcs5_keyivgen(password)
    cipher
  end

end

controller:

def create
  @shop = Shop.new(shop_params)
  @shop.user = current_user
  @shop.cache_images

  if @shop.save
    redirect_to account_path, notice: 'Shop created!'
  else
    render :new
  end
end

def update
  @shop = current_user.shop
  @shop.assign_attributes(shop_params)
  @shop.cache_images

  if @shop.save
    redirect_to account_path, notice: 'Shop updated.'
  else
    render :edit
  end
end

view:

= f.file_field :logo
= f.hidden_field :logo_cache

- if @shop.logo.file?
  %img{src: @shop.logo.url, alt: ''}