Simple RoR problem with file_column / rmagick

Rails
#1

At least I suspect it’s a simple problem. I’m quite new.
I have written a class to store images, and generate thumbnails for
them. This works well.
However I’ve been having a lot of trouble getting it to keep track of
the files size.

1: class Photo < ActiveRecord::Base
2: file_column :image, :magick => {
3: :versions => {
4: “thumb” => {
5: :transformation => Proc.new { |image|
6: image.change_geometry!(‘160x120’) { |cols, rows,
img|
7: img.thumbnail!(cols, rows)
8: }
9: },
10: :attributes => { :quality => 50 }
11: }
12: }
13: }
14: end

With rmagick it’s possible to access the size like so:
Magick::ImageList.new(image_address).filesize

So I was thinking of adding a method:
def getsize
Magick::ImageList.new(image).filesize #or should this be
@image?
end

Or perhaps this underneath line 5:
@size = image.filesize

However both of these trigger errors. Could someone help?

Thanks!

#2

Aaaarg wrote:

def getsize
    Magick::ImageList.new(image).filesize     #or should this be

@image?
end

Or perhaps this underneath line 5:
@size = image.filesize

However both of these trigger errors. Could someone help?

Try either

Magick::ImageList.new(image).cur_image.filesize

or

Magick::Image.read(image).first.filesize

–
We develop, watch us RoR, in numbers too big to ignore.

#3

Thank you very much for the suggestions but it’s not quite what I’m
looking for.
I think what I’m having trouble with is more basic.

What I want to be able to is access the file size (and other
attributes) outside, from an rhtml file.
I have done this successfully by adding this line to the rhtml file:
<%= Magick::ImageList.new(photo.image).filesize %>

Although this works, it incurs a massive time penalty, somewhere
around 1 second per image.

I think the best method would be to get the size and store it when the
image is saved, which is why I thought of putting this beneath line 5:
@size = image.filesize

however that does nothing so far as I can tell.

I had another thought - defining this function at the start of the
class:
def store_size(image)
@size = image.filesize
end

and adding this beneath line 5:
store_size(image)

however this gives the error ‘undefined method `write_description’ for
Photo:Class’

So how do I call a function on the object rather than the class from
the block starting at line 5?

Thanks again!

#4

add a feild ‘size’ to your table and this will work

class some_class

before_save :store_size

def store_size
size = image.filesize
end

…
end

#5

Hi, thanks for the reply. Still not quite what I’m looking for
unfortunately.

I’ve posted the relevant code online for anyone willing to look:
http://pastie.caboo.se/141484

It is what I assumed would work, and I think it would except that when
I call store_image_description from where I do, it tries to call it on
the class, and not the object.

Any ideas?

#6

Already solved?

I had to patch file_column a little bit. The Problem is, that you can’t
access the image anywhere but on the filesystem. “image” holds only the
name of the file. So 2 options:

  1. Before store: load the file again into memory and get the size
  2. Patch file_column to call some “after_render” method with the image,
    so you can do your info extraction.

You could insert this method in magic_file_column.rb in BaseUploaded

def call_after_render(img,version)
if options[:after_render]
options[:after_render].each do |sym|
@instance.send(sym,img,version)
end
end
end

now call this method from within transform_with_magick where apropriate.

in your model you should use sth like
file_column :image, :after_render => [:myinfoextractor]
private
def myinfoextractor(img,version)
self.width=img.columns
end

I think that should give you some clue what to do…

#7

Simple solution: attachment_fu

#8

Ar Chron wrote:

Simple solution: attachment_fu

Q: How can I tune my Mercedes?
A: Buy a Porsche. :wink:

#9

Sounds like a winner to me!

('course, I’ve always been partial to Porche’s… maybe cause I got to
use one for HS prom… what a memory!)

As for the Rails bit, I think Ar’s right on. If you’ve already got
rmagick working, just slap in attachment_fu. It’s dirt-easy and quite
powerful and configurable. If you are having to monkeypatch
file_column to access size data and the like, then I really, seriously
recommend attachment_fu and spend the rest of the otherwise-
monkeypatch-time celebrating your fine Rails app over beers or lattes.

That’s my strategy, at any rate.

-Danimal

On Apr 9, 12:22 am, Peter S. [email protected]