I wrote a post on compressing images with TinyPNG, but that 500 image limit ran out fast!  So I decided to see if I could put together my own image optimization service.

After a little digging I found the image_optim gem.  It’s very nice and straightforward, and includes image_optim_pack gem which installed all the compression libraries as well – making for a very hassle free set-up.  After getting those installed and setting up my rails project, it really came down to a simple interface with one controller and view.

Controller:

require 'open-uri'
require 'image_optim'
require 'fileutils'
 
class WelcomeController < ApplicationController
  def index
    Dir.glob("public/tmp/*").
      select{|f| File.mtime(f) < (Time.now - (60*120)) }.
      each{|f| File.delete(f) }
 
    image = params[:i]
    extension = File.extname(image)
 
    acceptable_extensions = [".jpg", ".gif", ".png"]
 
    return @json = "{\"error\":\"only jpg, png, and gif can be resized\"}" if !acceptable_extensions.include?( extension.downcase )
 
    value = ""; 8.times{value  << (65 + rand(25)).chr}
    tmp_image = "public/tmp/#{value}#{extension}"
 
    open(tmp_image, 'wb') do |file|
      file << open(image).read
    end
 
    before_filesize = (File.size(tmp_image) * 0.001).floor
 
    image_optim = ImageOptim.new
    image_optim = ImageOptim.new(:pngout => false)
    image_optim = ImageOptim.new(:nice => 10)
 
    image_optim.optimize_image!(tmp_image)
 
    after_filesize = (File.size(tmp_image) * 0.001).floor
 
    tmp_image = "http://yourdomain.com/tmp/#{value}#{extension}"
 
    @json = "[{\"dest\":\"#{tmp_image}\",\"src_size\":#{before_filesize},\"dest_size\":#{after_filesize}}]"
  end
 
end

View:

1

<%= raw @json %>

I’m including open-uri to download the image to be compressed, image_optim to do the compressing, and fileutils to check the file size.

1. I start with the Dir.glob to first delete any temporary images that are over 120 hours old.
2. Then I grab the image from the url provided with the i param, and make sure it has the right extention
3. Then generate a random string and create the temporary filename and save the image there
4. Then I optimize the image and save over it
5. Then I just write out the JSON I want by hand – I wrote it to resemble smush.it’s syntax

You will need to change “yourdomain.com” to your actual domain here, looking back I should have done that programmatically – but it’s not a big deal.

I have to whole project available on git hub for download.

I keep forgetting the rails generator syntax for migrations :X  I can never find just a quick easy guide for it – so I thought I’d write one up!

Instructions

1. cd …
   obviously first make sure your in the main project folder in the console
2. export RAILS_ENV=environment
   Also, make sure you’re in the right environment, you will probably want to make the change first in your test or development environment and then put it to production
3. rails g migration AddColumnToModel column_name:column_type
   Here’s the main part, on  older versions rails g migration will be script/generate migration.  The “AddColumnToModel” syntax is important and should relate to the migration you’re making like “AddEmailToUser” and then at the end you can add a “column_name:column_type” reference for each column you want to add, for instance with the last example you would put “email:string“
4. rake db:migrate
   run the migration and add those columns to the database!  You’ll probably want to review the migration that was generated first though – it’ll be the latest file in the …/db/migrate directory
   

AND MAKE SURE TO RESTART YOUR SERVER AFTER MAKING A CHANGE

Column Types

• binary: for files/ data blob
• boolean: true/false
• date: only date: (year, month, day)
• datetime: date + time
• decimal: precise decimal numbers – for when math neds to be accurate
• float: decimal numbers
• integer: whole numbers
• string: 255 max alphanumeric characters
• text: unlimited alphanumeric characters
• time: only time (hours, minutes, seconds)
• timestamp: same as datetime

And, if you make a mistake a quick way to go back and fix it is “rake db:migrate:redo” that will undo your last change, and re-run it.

Also, if you want to only run “rake db:migrate:up VERSION=20090408054532”

In a pinch you can also run a migration by hand in the console with the following format:
ActiveRecord::Migration.add_column :table, :column_name, :column_type

References:
http://stackoverflow.com/questions/11889048/is-there-documentation-for-the-rails-column-types
http://stackoverflow.com/questions/15162055/rails-generate-migration
http://stackoverflow.com/questions/7694487/ruby-on-rails-how-can-i-revert-a-migration-with-rake-dbmigrate