Railsでファイルアップロードするとき

new.html.erb

<%= form_for :user, :url => {:action => :create}, :html => {:method => :post, :multipart => true}  do |f| %>
  <%= f.text_filed :name %>
  <%= f.file_filed :image %>
<% end %>

users_controller.rb

def create
  @user = User.new(:name => params[:user][:name])
  if params[:user][:image].present?
    File.open(filepath, 'wb') do |f|
      f.write(params[:user][:image].read)
    end
  end
  @user.save!
end