timing of paperclip thumbnail generation

Question

Why exactly does paperclip execute convert when a File is assigned to the attachment instead of doing all that heavy work when save is called.

This seems like it's bad:

ar_obj.attachment = File.open('...') 
#copy file to /tmp 
#styles.length.times do { identify & convert } 
ar_obj.save 
# copy original & thumbnails in place.

I'm not sure this makes much sense at all. Why try to convert an unvalidated attachment?

For example: try attaching a 10G image - it takes FOREVER to complete even if you have a validation on size (say <5MB) because the 10G image is still re-processed into each style that you have. It isn't until save is called that the error gets added.

There must be a good reason for this, please enlighten me.

You should accept jyurek's answer. He wrote paperclip after all. — gtd, Apr 08 '11 at 04:38

score 1 · Answer 1 · answered Apr 07 '11 at 20:15

It was originally because an invalid image (like if you tried to upload a mp3 when you were expecting a jpg) was a validation error, and needed to be discovered prior to saving so you could display a proper error to the user.

Even validations on size in Rails mean the connection will be held open that long as the upload happens. If you really want to fail fast in that case, you should prevent large uploads on the Apache/nginx level.

score 0 · Answer 2 · answered Apr 06 '11 at 15:38

0

I don't know the exact reason why this is done, but I found it weird too. I usually solve it by using the DelayedPaperclip gem, which postpones processing of attachments to a DelayedJob worker.

https://rubygems.org/gems/delayed_paperclip

answered Apr 06 '11 at 15:38

Edwin V.

1,327
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this, unfortunately, isn't feasible. I need the processed image to render the next page. Thanks though! – jsharpe Apr 06 '11 at 18:05

timing of paperclip thumbnail generation

2 Answers2