RE: Problem using rmagick in model class


#1

I think that in the code that didn’t work, you were, in effect, creating
a class called Registrant::Magick::ImageList, because the require was
inside the class definition (this is how mixins do their magic).
However, it seems that doesn’t apply if you use require inside a
method inside a class - your controller code that works.

Either put the require outside the class or module, or inside a method
to get the behavior you want.


From: David R. [mailto:removed_email_address@domain.invalid]
Sent: Monday, December 12, 2005 9:00 PM
To: removed_email_address@domain.invalid
Subject: Re: [Rails] Problem using rmagick in model class

Doh.

So, it might be helpful if I understood why my previous code, where all
of this was in the controller, worked fine, even when the require_gem
statement was called within a class method. The controller method looked
like this:

def upload_image(*some_args)
require_gem ‘rmagick’
#do stuff with Magick::ImageList
end

On 12/12/05, Tom F. < removed_email_address@domain.invalid mailto:removed_email_address@domain.invalid >
wrote:

Move the ‘require_gem “rmagick”’ line outside the class definition for
Registrant

require_gem ‘rmagick’
class Registrant < ActiveRecord::Base


From: David R. [mailto:removed_email_address@domain.invalid]
Sent: Monday, December 12, 2005 10:04 AM
To: removed_email_address@domain.invalid
Subject: [Rails] Problem using rmagick in model class

I’m refactoring some code in order to conform to “the right way” of
doing things. That is, I’m moving my image-saving code from my
controller to my model. What worked fine in the controller class is not
working in the model class.

Currently, my code looks somewhat like this:
##############
class RegistrantsController < ApplicationController
def upload_image
@registrant = Registrant.find(session[:registrant_id])
if request.post?
if(params[:crop_params])
@registrant.save_image(params[:image_to_crop],
params[:crop_params])
redirect_to :action => :index
else
@registrant.image = params[:registrant][:image]
File.chmod(0644, @registrant.image)
end
end
end
end

class Registrant < ActiveRecord::Base
require_gem ‘rmagick’

def save_image(image_to_crop, crop_params)

img_base = RAILS_ROOT + "/public/images/registrants/"
img_file =  self.id.to_s + ".jpg"
y, x, w, h = crop_params.split(',')

img = Magick::ImageList.new(image_to_crop) # this is throwing

“uninitialized constant ImageList”

img.crop!(x.to_i, y.to_i, w.to_i, h.to_i)
img.resize!(120, 120)
color_thumb = img.resize(32, 32)
grey_img = img.quantize(256, Magick::GRAYColorspace)
img.write(img_path + img_filename)
grey_img.write(img_base + 'greyscale/' + img_filename)
color_thumb.write(img_base + 'thumbnail/' + img_filename)

end
end
##############

Note the comment in there (# this is throwing “uninitialized constant
ImageList”)

Can anyone see what I’ve done wrong, or otherwise help out?

Thanks,
David R.


#2

Ara, your suggestion to preface the call with :: worked perfectly.

I’m gonna stab in the dark and assume my use of file_column elsewhere in
the
model may be to blame.

Thanks
David R.

On 12/13/05, removed_email_address@domain.invalid removed_email_address@domain.invalid wrote:

your controller code that works.

Rails mailing list
removed_email_address@domain.invalid
http://lists.rubyonrails.org/mailman/listinfo/rails


David R.
Webmaster, SXSW Conferences and Festivals
SXSW 2005 - March 11-20, 2005 - Austin, Texas
http://sxsw.com/


#3

On Mon, 12 Dec 2005, Tom F. wrote:

I think that in the code that didn’t work, you were, in effect, creating a
class called Registrant::Magick::ImageList, because the require was inside
the class definition (this is how mixins do their magic). However, it seems
that doesn’t apply if you use require inside a method inside a class -
your controller code that works.

Either put the require outside the class or module, or inside a method
to get the behavior you want.

‘require’ cares not where it’s called from. try prefacing the ‘Magick’
constant with ‘::’ to make sure you are refering to the top-level Magick
module. in general you should always do this since:

harp:~ > cat a.rb
class Foo; end

class Bar
p Foo # gets top level foo
end

class FooBar
Foo = 42
p Foo
p ::Foo # gets top level foo
end

harp:~ > ruby a.rb
Foo
42
Foo

rails does some voodoo with const_missing that may have caused your
referencing
it to define one in your model - or perhaps you have another Magick
const
defined somewhere else in your code, since the code is your model now
this
should be quite easy to test.

regards.

-a