attachment_fu, how to regenerate thumbnails

i'm using this plugin for files and images uploads.
it has a very useful feature that generate thumbnails of every
uploaded image, based on the geometry given in the model definition.
now i want to change the size of one of the thumbnail: how can i re-
generate them for the already saved image?

i found this
but i don't understand how to use it.

why don't you just write a migration that loops all of those objects
with the old thumbnail-information and call the method that generates
the thumbnails again.

like this:


i'd like to add: i don't know your app and i don't use attachment_fu
either. thus, the line above is obviously not working. it's just to
give you an idea.

I use a method that rebuilds in my attachment model class:

  # use attachment_fu protected methods to remake thumbs
  def remake_thumbnails!
    self.thumbnails.each {|thumb| thumb.destroy}
    temp_file = create_temp_file
    attachment_options[:thumbnails].each do |suffix, size|
      self.create_or_update_thumbnail(temp_file, suffix, *size)

If you want a rake task, just loop through all your attachment records
and call it. I'm using something similar to this:

namespace :images do
  desc "Rebuild all thumb images made by attachment_fu"
  task :rebuild_thumbnails => :environment do
    conditions = "(whatever you need)"
    count = Image.count(:all, :conditions => conditions) # image is an
attachment_fu model
    done = 0
    chunk_size = 500
    (0...(count/chunk_size)).each do |i|
      Image.find(:all, :offset => i*chunk_size, :limit =>
chunk_size, :conditions => conditions).each do |image|
        done = done + 1
        # next if < 46520 # to resume a stopped run
        percent = "%.2f" % ((done/count.to_f)*100)
        puts "#{} #{percent}% done"


This is old thread but i need some help!

I’d like to take foz’s solution for my project using attachment_fu.

I am going to make link to remake thumbs in my view, and i don’t need to rake task.

But I don’t know where I should put ‘remake_thumbnails!’ method in.

I’ve tried to put the method in ‘attachment_fu.rb’, but it’s not working.

Should I put it in my upload model or wherelse?

And how can I call this method from view or controller?

I am a really beginner in web development using Rails and Ruby.

it will many thanks if you help me.

2009년 11월 30일 월요일 오후 1시 15분 33초 UTC+9, foz 님의 말: