Rails Paperclip & Multiple File Uploads

Question

I am looking for a solution to give the user the ability to upload multiple images through one file_field. I have looked in to options such a Jquery File Upload and Uploadify but have yet to come across good examples with a working solution.

I already have multiple images setup,

 has_attached_file :asset,
                   :styles => { :large => "640x480", :medium => "300x300", :thumb => "100x100" },
                   :storage => :s3,
                   :s3_credentials => "#{Rails.root}/config/s3.yml",
                   :path => "/:contributor_id/:listing_name/:filename"

Right now I am displaying 5 individual file_fields

def new
  @listing = Listing.new
  5.times {@listing.assets.build }

  respond_to do |format|
    format.html # new.html.erb
    format.json { render json: @listing }
  end
end

I would like to have

<%= f.file_field :asset, :multiple => true %>

That allows the user to select multiple files in their file browser. But how can I process these with a nested model? And get them to upload.

Answer 1

So there are a few issues here.

First, Paperclip's has_attached_file method isn't an association to many files. It looks like you're trying to build an "asset" as if it's a Rails association. All Paperclip does is put a couple of fields into your table to store some meta-data about the file and you get one attached file per declaration of has_attached_file. If you want to attach 5 files, you would need to do something like:

has_attached_file :asset1
has_attached_file :asset2
has_attached_file :asset3
has_attached_file :asset4
has_attached_file :asset5

OR, alternatively, you could create another model just to store the files. For example:

class Listing < ActiveRecord::Base
  has_many :assets
end

class Asset < ActiveRecord::Base
  belongs_to :listing
  has_attached_file :picture
end

That way, you could have multiple assets attached to one listing (you didn't say what the original object was so I just called it "listing").

Second, there is no such thing as a multiple file upload in HTML (and, as such, the file_field method doesn't take a :multiple => true argument. You'll have to use something beyond Rails built-in form handling if you want multiple-file upload. Uploadify is a decent choice (that I've used before). There is a gem that will transform file fields to use uploadify (and will support the :multiple => true syntax that you want): https://github.com/mateomurphy/uploadify_rails3/wiki. However, I cannot vouch for how good it is.

My advice would be to start step-by-step. Uploading via Flash to Rails can be a complicated process that involves dealing with the CSRF meta-tag and other fields in your form. Start by making a form that allows a user to upload one file and stores it through Paperclip. Then maybe break the has_attached_file declaration into another model so that you can have 1 or many files associated with a model (as shown in the multi-model code block above). Then try adding Uploadify or another alternative. Ernie Miller has a decent tutorial on integrating Uploadify: http://erniemiller.org/2010/07/09/uploadify-and-rails-3/.

To start, remember that has_attached_file can only attach one file. When you try calling @listing.assets there is no "assets". There is an asset. You need to create a separate model yourself and use Rails' associations if you want multiple files.