Downloading data as xls or Excel without a Gem

download_xls.rb

# This gist demonstrates - How to download data from database in excel or xls format in Ruby on Rails
# Tested with - Ruby 1.9.3, rails 3.2.1, db - postgres

class DownloadsController < ApplicationController
  before_filter :define_header, :except => :index

  def index
    ...
  end

  def download_choclates
    @choclates = Choclate.all
    
    respond_to do |format|
      format.html { render :partial => 'download_choclates' }
    end
  end

  private
  # sets the header. You can specify the file name
  # For my project I am sending the name of the file in params
  # so I use 
  # headers['Content-Disposition'] = "attachment; filename=#{params[:name]}.xls"

  def define_header
    headers['Content-Type'] = "application/vnd.ms-excel"
    headers['Content-Disposition'] = "attachment; filename=filename.xls"
    headers['Cache-Control'] = ''
  end
end

# Partial to be rendered
# _download_choclates.html.erb
<table border="1">
  <tr>
    <th>Id</th>
    <th>Description</th>
    <th>Price</th>
    <th>Feedback</th>    
    <th>Created At</th>
    <th>Updated At</th>
  </tr>

<% @choclates.each do |choclate| %>
  <tr>
    <td><%= choclate.id %></td>
    <td><%= choclate.description %></td>
    <td><%= choclate.price %></td>
    <td><%= choclate.feedback %></td>
    <td><%= choclate.created_at %></td>
    <td><%= choclate.updated_at %></td>
  </tr>
<% end %>
</table>