How do I pass a variable watermark path to a paperclip watermark processor?

问题:

I have watermarks, galleries, and photos models.

Gallery belongs_to Watermark Photo belongs_to Gallery

class Photo < ActiveRecord::Base   before_save :save_dimensions, :set_orientation   belongs_to :gallery    has_attached_file :image,     :processors => [:watermark],     :styles => {       :thumbnail => ["80x80>"],       :small => {         :geometry => "200x200>",         :watermark_path => "#{gallery.watermark.image.path(:small)}",         :position => "Center"       },       :medium => {         :geometry => "400x400>",         :watermark_path => "#{gallery.watermark.image.path(:medium)}",         :position => "Center"       },       :large => {         :geometry => "600x600>",         :watermark_path => "#{gallery.watermark.image.path(:large)}",         :position => "Center"       }     },     :path => ":rails_root/public/images/galleries/:gallery_id/:id/:style_:basename.:extension",     :url => "galleries/:gallery_id/:id/:style_:basename.:extension"   validates_attachment_presence :image   validates_attachment_content_type :image, :content_type => ['image/jpeg', 'image/png']   attr_protected :image_file_name, :image_content_type, :image_file_size  end 

With this I get undefined local variable or method 'gallery'. If I try like this with :gallery_watermark_path defined using Paperclip.interpolations it silently fails.

:watermark_path => ":gallery_watermark_path" 

The :gallery_watermark_path doesn't get processed by Paperclip.interpolations:

development.log:

[paperclip] identify -format %wx%h '/tmp/stream20110620-30644-1j6i9in.jpg[0]' 2>/dev/null [paperclip] convert '/tmp/stream20110620-30644-1j6i9in.jpg' '-resize' '80x80>' '-auto-orient' '/tmp/stream20110620-30644-1j6i9in20110620-30644-1mcqvox' 2>/dev/null [paperclip] identify -format %wx%h '/tmp/stream20110620-30644-1j6i9in.jpg[0]' 2>/dev/null [paperclip] convert '/tmp/stream20110620-30644-1j6i9in.jpg' '-resize' '200x200>' '-auto-orient' '/tmp/stream20110620-30644-1j6i9in20110620-30644-60zlb' 2>/dev/null [paperclip] composite '-gravity' 'Center' ':gallery_watermark_path' '/tmp/stream20110620-30644-1j6i9in20110620-30644-60zlb' '/tmp/stream20110620-30644-1j6i9in20110620-30644-60zlb' 2>/dev/null [paperclip] An error was received while processing: #<Paperclip::PaperclipError: There was an error processing the watermark for stream20110620-30644-1j6i9in> [paperclip] identify -format %wx%h '/tmp/stream20110620-30644-1j6i9in.jpg[0]' 2>/dev/null [paperclip] convert '/tmp/stream20110620-30644-1j6i9in.jpg' '-resize' '400x400>' '-auto-orient' '/tmp/stream20110620-30644-1j6i9in20110620-30644-1ronidq' 2>/dev/null [paperclip] identify -format %wx%h '/tmp/stream20110620-30644-1j6i9in.jpg[0]' 2>/dev/null [paperclip] convert '/tmp/stream20110620-30644-1j6i9in.jpg' '-resize' '600x600>' '-auto-orient' '/tmp/stream20110620-30644-1j6i9in20110620-30644-1ikfy72' 2>/dev/null 

In short, how do I pass the watermark variable to the processor?

回答1:

You could use a proc for the styles:

  has_attached_file :image,     :processors => [:watermark],     :styles => proc { |attachment|       {         :thumbnail => ["80x80>"],         :small => {           :geometry => "200x200>",           :watermark_path => attachment.instance.gallery.watermark.image.path(:small),           :position => "Center"         },         :medium => {           :geometry => "400x400>",           :watermark_path => attachment.instance.gallery.watermark.image.path(:medium),           :position => "Center"         },         :large => {           :geometry => "600x600>",           :watermark_path => attachment.instance.gallery.watermark.image.path(:large),           :position => "Center"         }       }     },     [...] 

But sometimes, the proc is called before the instance get all its attributes (so sometimes gallery may be nil because you may have assigned image before gallery_id).

回答2:

The watermark_path needs to be a Pathname, try to use Rails.root.join like this:

has_attached_file :image, :processors => [:watermark], :styles => {   :thumbnail => ["80x80>"],   :small => {     :geometry => "200x200>",     :watermark_path => Rails.root.join("#{gallery.watermark.image.path(:small)}")     :position => "Center"   },   :medium => {     :geometry => "400x400>",     :watermark_path => Rails.root.join("#{gallery.watermark.image.path(:medium)}")     :position => "Center"   },   :large => {     :geometry => "600x600>",     :watermark_path => Rails.root.join("#{gallery.watermark.image.path(:large)}"),     :position => "Center"   } } [...] 

I hope that helps you,

cheers.

文章来源: How do I pass a variable watermark path to a paperclip watermark processor?