Controller.rb

get :upload, :map => "/upload" do
  render 'Form.haml'
end
  
post :upload, :map => "/upload" do
  @kitten = Kitten.create(:image => params[:file][:tempfile], :type => params[:type], :age => params[:age])
  redirect @kitten.save ? "/kitten/#{@kitten.id}" : "/upload"
end  

get :kitten, :map => "/kitten/:id" do
  @kitten= Kitten.find_by_id(params[:id])
  render 'image.haml'
end

Form.haml

- form_tag '/new-kitten', :class => 'new-kitten', :method => 'post', :enctype => "multipart/form-data" do
  - field_set_tag do
    %p
      = label_tag :name, :class => 'first'
      = text_field_tag :name, :value => "kitten's name"
    %p
      = label_tag :file, :class => 'first'
      = file_field_tag :file
    %p
      = label_tag :age, :class => 'age', :caption => "Age (in Years)"
      = text_field_tag :age, :value => 1
    %p
      = label_tag :type, :class => 'type', :caption => "Type"
      = text_field_tag :type, :value => "persan"
    %p
  - field_set_tag(:class => 'buttons') do
    = submit_tag "Add"

image.haml

= image_tag("/image/#{@kitten.image.id}")