error facing while cropping photo using Paperclip in Rails 3

问题

Hi i am trying to crop photo using paperclip and imagemagick. I am facing some error while cropping photo. following is the error stack:

?[32mCommand?[0m :: convert "C:/Users/Anand/AppData/Local/Temp/120120924-3568-tx
2bxy.jpg[0]" -crop 103x103+0+0 -auto-orient "C:/Users/Anand/AppData/Local/Temp/1
20120924-3568-tx2bxy20120924-3568-16dij9c"
?[32mCommand?[0m :: file -b --mime "C:/Users/Anand/AppData/Local/Temp/120120924-
3568-tx2bxy20120924-3568-16dij9c"
[paperclip] Error while determining content type: Cocaine::CommandNotFoundError
?[32mCommand?[0m :: identify -format %wx%h "C:/Users/Anand/AppData/Local/Temp/12
0120924-3568-tx2bxy.jpg[0]"
  ?[1m?[36m (0.0ms)?[0m  ?[1mrollback transaction?[0m
Completed 500 Internal Server Error in 145552ms

NoMethodError (undefined method `exitstatus' for nil:NilClass):
  app/models/user.rb:14:in `reprocess_photo'
  app/models/user.rb:14:in `reprocess_photo'
  app/models/user.rb:14:in `reprocess_photo'
  app/models/user.rb:14:in `reprocess_photo'
  app/models/user.rb:14:in `reprocess_photo'
  app/models/user.rb:14:in `reprocess_photo'
  app/models/user.rb:14:in `reprocess_photo'
  app/controllers/users_controller.rb:67:in `block in update'
  app/controllers/users_controller.rb:66:in `update'


  Rendered E:/Ruby192/lib/ruby/gems/1.9.1/gems/actionpack-3.2.8/lib/action_dispa
tch/middleware/templates/rescues/_trace.erb (10.0ms)
  Rendered E:/Ruby192/lib/ruby/gems/1.9.1/gems/actionpack-3.2.8/lib/action_dispa
tch/middleware/templates/rescues/_request_and_response.erb (1.0ms)
  Rendered E:/Ruby192/lib/ruby/gems/1.9.1/gems/actionpack-3.2.8/lib/action_dispa
tch/middleware/templates/rescues/diagnostics.erb within rescues/layout (51.0ms)
Exiting

model/user.rb file:

class User < ActiveRecord::Base
  attr_accessible :name,:photo,:crop_x,:crop_y,:crop_w,:crop_h
  has_attached_file :photo,:styles => {:small=>"100x100#",:large=>"500x500>"},:processors => [:cropper]
  attr_accessor :crop_x,:crop_y,:crop_w,:crop_h
  after_update :reprocess_photo,:if=>:cropping?

  def cropping?
    !crop_x.blank? && !crop_y.blank? && !crop_w.blank? && !crop_h.blank?
  end

  private 

  def reprocess_photo
    photo.reprocess!
  end

end

my lib/paperclip_processros/cropper.rb

module Paperclip
  class Cropper < Thumbnail
    def transformation_command
      if crop_command   
        #this generates command :
        #this is right #convert "C:/Users/Anand/AppData/Local/Temp/1.jpg[0]" -crop 102x102+0+0 -auto-orient "C:/Users/Anand/AppData/Local/Temp/120120924-2336-qbzroo20120924-2336-1jqbiiv.jpg"
        crop_command + super.first.sub(/ -crop \S+/, '')
      else
        super
      end
    end

    def crop_command
      target = @attachment.instance
      if target.cropping?
        " -crop #{target.crop_w}x#{target.crop_h}+#{target.crop_x}+#{target.crop_y} "
      end
    end
  end
end

my config/env./dev.rb

 Paperclip.options[:swallow_stderr] = false
 Paperclip.options[:command_path] = "C:/Program Files/ImageMagick-6.7.9-Q16/"

when m updating a photo after crop, it goes in loop. What could be the solution?

回答1:

I'm pretty sure you are running into the same issue that I initially had, whereby the reprocess! method was saving the ActiveRecord parent, which was then trigging the after_update callback, which resulted in your reprocess_photo method being called again. The end result is a somewhat recursive loop that won't stop until your machine runs out allocatable memory.

The easy fix for this is add a boolean attribute called processing which will allow you to determine whether or not we're already reprocessing the image.

attr_accessor :processing

Then change your reprocess_photo to return if the image is already being processed.

  def reprocess_photo
    # don't crop if the user isn't updating the photo
    #   ...or if the photo is already being processed
    return unless (cropping? && !processing)
    self.processing = true
    photo.reprocess!
    self.processing = false
  end

回答2:

Try changing

 Paperclip.options[:command_path] = "C:/Program Files/ImageMagick-6.7.9-Q16/"

to

  Paperclip.options[:command_path] = 'C:/PROGRA~1/IMAGEM~1.0-Q'

Seems like image-Magick is not found

来源：https://stackoverflow.com/questions/12559769/error-facing-while-cropping-photo-using-paperclip-in-rails-3