in rails, how to return records as a csv file

Question

I have a simple database table called "Entries":

class CreateEntries < ActiveRecord::Migration   def self.up     create_table :entries do |t|       t.string :firstName       t.string :lastName       #etc.       t.timestamps     end   end    def self.down     drop_table :entries   end end 

How do I write a handler that will return the contents of the Entries table as a CSV file (ideally in a way that it will automatically open in Excel)?

class EntriesController < ApplicationController    def getcsv     @entries = Entry.find( :all )      # ??? NOW WHAT ????    end  end 

Answer 1

FasterCSV is definitely the way to go, but if you want to serve it directly from your Rails app, you'll want to set up some response headers, too.

I keep a method around to set up the filename and necessary headers:

def render_csv(filename = nil)   filename ||= params[:action]   filename += '.csv'    if request.env['HTTP_USER_AGENT'] =~ /msie/i     headers['Pragma'] = 'public'     headers["Content-type"] = "text/plain"      headers['Cache-Control'] = 'no-cache, must-revalidate, post-check=0, pre-check=0'     headers['Content-Disposition'] = "attachment; filename=\"#{filename}\""      headers['Expires'] = "0"    else     headers["Content-Type"] ||= 'text/csv'     headers["Content-Disposition"] = "attachment; filename=\"#{filename}\""    end    render :layout => false end 

Using that makes it easy to have something like this in my controller:

respond_to do |wants|   wants.csv do     render_csv("users-#{Time.now.strftime("%Y%m%d")}")   end end 

And have a view that looks like this: (generate_csv is from FasterCSV)

UserID,Email,Password,ActivationURL,Messages <%= generate_csv do |csv|   @users.each do |user|     csv << [ user[:id], user[:email], user[:password], user[:url], user[:message] ]   end end %> 

Answer 2

I accepted (and voted up!) @Brian's answer, for first pointing me to FasterCSV. Then when I googled to find the gem, I also found a fairly complete example at this wiki page. Putting them together, I settled on the following code.

By the way, the command to install the gem is: sudo gem install fastercsv (all lower case)

require 'fastercsv'  class EntriesController < ApplicationController    def getcsv       entries = Entry.find(:all)       csv_string = FasterCSV.generate do |csv|              csv << ["first","last"]             entries.each do |e|               csv << [e.firstName,e.lastName]             end           end           send_data csv_string, :type => "text/plain",             :filename=>"entries.csv",            :disposition => 'attachment'    end   end