How to send multiple files using dropzone.js with Rails? - ruby-on-rails-4

Question

Using Rails 4 Paperclip and SimpleForm.
I'm trying to make a multiple file upload. For this I am using Dropzone.js upon customer request.
It is a form where I have: Name, Address, Phone, Documents, Certificates.
So I created 2 separate dropzones for documents and certificates.
This is my code on the form:
= simple_form_for(#user, html: {multipart: true, autocomplete: 'off' }) do |f|
= f.input :name, label: false # Column name in table User
= f.input :address, label: false # Column address in table User
#attachments-documents.dropzone # Column document in table User
#attachments-certificates.dropzone # Column certificate in table User
:javascript
var attachments_1 = new Dropzone("div#attachments-documents", { url: "#{upload_file_biddings_path}"});
var attachments_2 = new Dropzone("div#attachments-certificates", { url: "#{upload_file_path}"});
Dropzone.options.attachmentsDocuments = {
paramName: 'user[document]',
maxFilesize: 20,
parallelUploads: 3,
addRemoveLinks : true,
autoProcessQueue: false
}
Dropzone.options.attachmentsCertificates = {
paramName: 'user[certificate]',
maxFilesize: 20,
parallelUploads: 3,
addRemoveLinks : true,
autoProcessQueue: false
}
Controller:
Class User < ApplicationController
[...]
def create
work = Work.new(work_params)
if work.save
flash[:notice] = "Se ha creado correctamente la Obra."
redirect_to :action => :index
else
work.errors.messages.each do |attribute, error|
puts error.to_s
puts error
end
flash[:error] = "Ha ocurrido un error en el sistema."
redirect_to :action => :index
end
end
def update
work = Work.find(params[:id])
if work.update_attributes(work_params)
flash[:notice] = "Se ha actualizado correctamente los datos."
redirect_to :action => :index
else
work.errors.messages.each do |attribute, error|
flash[:error] = attribute " " + flash[:error].to_s + error.to_s + " "
end
# Load new()
#work = work
render :edit, layout: false
end
end
def upload_file
puts params
render :json => params
end
private
def work_params
params.require(:user).permit(:name, :address, :document, :certificate)
end
end
But here I have 2 problems.
1) When I put a file into the Dropzone, by default calls the "upload_file" function when the files should be uploaded when you click on my submit button and GO to create function.
2) I did a test upload multiple files with another JS, however only managed to climb the last of them. Ie:
I put in my file_field 3 files: file1, file2, file3. But in DB, only recorded the file3.
Has anyone uploaded multiple files with Paperclip? Using JS Dropzone.js or other successfully?
If so, I'd like to share knowledge.