Trying to upload multiple files - Document(#70285786863740) expected, got ActionDispatch::Http::UploadedFile(#70285766684260) when

I'm trying to use Dragonfly to upload multiple files at a time and store them. I was able to successfully upload and store a single file by adding a document_uid and document_name to my case model, but now I want to create the ability to upload multiple files per case object so I need to have my document_uid and document_name in their own table with a FK to the case table.

I'm currently getting the error: Document(#70285786863740) expected, got ActionDispatch::Http::UploadedFile(#70285766684260)

app/models/case.rb

class Case < ActiveRecord::Base
  has_many :documents

  attr_accessible :documents
end

class Document < ActiveRecord::Base

    belongs_to :case
    dragonfly_accessor :document    # defines a reader/writer for an uploaded document

  attr_accessible :document_uid, :document_name
end

view

<%= form_for(@case) do |f| %> 
    ...
    <%= f.file_field :documents, :multiple => true %>
    ...
<% end %>

So far i just have the default create method in my controller

 # POST /cases
  # POST /cases.json
  def create
    @case = Case.new(params[:case])

    respond_to do |format|
      if @case.save
        format.html { redirect_to @case, notice: 'Case was successfully created.' }
        format.json { render json: @case, status: :created, location: @case }
      else
        format.html { render action: "new" }
        format.json { render json: @case.errors, status: :unprocessable_entity }
      end
    end
  end

params:

Parameters: {"utf8"=>"✓", "authenticity_token"=>"KAsjoqrQT5HTNKsiH6bu3+MRKB0FKDLdP2Q/Gm9ZYdA=", "case"=>{"documents"=>[#<ActionDispatch::Http::UploadedFile:0x007fd95ebe97d8 @original_filename="Screen Shot 2014-01-25 at 8.59.17 PM.png", @content_type="image/png", @headers="Content-Disposition: form-data; name=\"case[documents][]\"; filename=\"Screen Shot 2014-01-25 at 8.59.17 PM.png\"\r\nContent-Type: image/png\r\n", @tempfile=#<Tempfile:/var/folders/5w/tkmvdtbn2xn98hjy655s67tw0000gn/T/RackMultipart20140727-43998-1go1ez0>>, #<ActionDispatch::Http::UploadedFile:0x007fd95ebe9760 @original_filename="Screen Shot 2014-03-02 at 8.38.22 AM.png", @content_type="image/png", @headers="Content-Disposition: form-data; name=\"case[documents][]\"; filename=\"Screen Shot 2014-03-02 at 8.38.22 AM.png\"\r\nContent-Type: image/png\r\n", @tempfile=#<Tempfile:/var/folders/5w/tkmvdtbn2xn98hjy655s67tw0000gn/T/RackMultipart20140727-43998-1kefqe0>>]}, "button"=>""}

What is causing this error and how can I circumvent it?

I ended up having to something similar to this: multiple image upload with dragonfly

app/models/case.rb

class Case < ActiveRecord::Base
  has_many :documents
  accepts_nested_attributes_for :documents
  attr_accessible :documents
end

class Document < ActiveRecord::Base

    belongs_to :case
    dragonfly_accessor :document    # defines a reader/writer for an uploaded document

  attr_accessible :document_uid, :document_name
end

Here's what my controller now looks like:

def create
    @case = Case.new(params[:case])

    #create the documents from the params
     unless params[:docs].nil?
        params[:docs].each do |doc|
        @case.documents << Document.create(:document => doc.tempfile, :filename => doc.original_filename, :mime_type => doc.content_type, :document_name => doc.original_filename)
       end
     end

    respond_to do |format|
      if @case.save
        format.html { redirect_to @case, notice: 'Case was successfully created.' }
        format.json { render json: @case, status: :created, location: @case }
      else
        format.html { render action: "new" }
        format.json { render json: @case.errors, status: :unprocessable_entity }
      end
    end
  end

View:

<%= form_for(@case) do |f| %> 
    ...
    <%= f.file_field :documents, :name => 'docs[]', :multiple => true %>
    ...
<% end %>

Basically i'm being forced to save the documents manually rather than automatically through the form helper.