# In new.html.erb
<%= file_field_tag 'upload[file]' %>

# In controller#create
@text = params[:upload][:file]

<%= form_tag 'controller/method_name', :multipart => true do %>
   <label for="file">Upload text File</label> <%= file_field_tag "file" %>
   <%= submit_tag %>
<% end %>

uploaded_file = params[:file]
file_content = uploaded_file.read
puts "file_content"

resources :contacts do
  collection do
    get 'import/new', to: :new_import  # import_new_contacts_path

    post :import, on: :collection      # import_contacts_path
  end
end

<%= form_for @contacts, url: import_contacts_path, html: { multipart: true } do |f| %>

  <%= f.file_field :import_file %>

<% end %>

def new_import
end

def import
  begin
    Contact.import( params[:contacts][:import_file] )

    flash[:success] = "<strong>Contacts Imported!</strong>"

    redirect_to contacts_path

  rescue => exception
    flash[:error] = "There was a problem importing that contacts file.<br>
      <strong>#{exception.message}</strong><br>"

    redirect_to import_new_contacts_path
  end
end

def import import_file
  File.foreach( import_file.path ).with_index do |line, index|

    # Process each line.

    # For any errors just raise an error with a message like this:
    #   raise "There is a duplicate in row #{index + 1}."
    # And your controller will redirect the user and show a flash message.

  end
end