回形針不為一種型號存儲替代尺寸，但為另一種型號存儲 (Paperclip is not storing alternative sizes for one model, but does for another)

問題描述

回形針不為一種型號存儲替代尺寸，但為另一種型號存儲 (Paperclip is not storing alternative sizes for one model, but does for another)

我有兩個附有圖片的模型。第一個是這樣定義的：

class Post < ActiveRecord::Base
  has_attached_file :cover_image, styles: { large: "750x750^", medium: "600x600>", thumb: "100x100>" }, default_url: ":style/missing.gif"
  validates_attachment_content_type :cover_image, content_type: /\Aimage\/.*\Z/
end

這很好用，在我的 /public 文件夾中總共存儲了 4 張圖像。

不過我的第二個模型......

class Lesson < ActiveRecord::Base
  has_attached_file :image, styles: { large: "750x750^", medium: "600x600>", thumb: "100x100>" }, default_url: ":style/missing.gif"
  validates_attachment_content_type :image, content_type: /\Aimage\/.*\Z/
end

... 僅將原始圖像存儲在名為 original 的文件夾中。

我的服務器日誌在 POST 請求中確實顯示了類似的內容：

Command :: file ‑b ‑‑mime '/var/folders/2b/q6z4f1fn58s83fbx77xwsk5h0000gn/T/64ecce8dbf7049731a63696ae4d7933020151207‑39937‑jxf7m7.jpg'
Command :: identify ‑format '%wx%h,%[exif:orientation]' '/var/folders/2b/q6z4f1fn58s83fbx77xwsk5h0000gn/T/64ecce8dbf7049731a63696ae4d7933020151207‑39937‑wmm770.jpg[0]' 2>/dev/null
Command :: identify ‑format %m '/var/folders/2b/q6z4f1fn58s83fbx77xwsk5h0000gn/T/64ecce8dbf7049731a63696ae4d7933020151207‑39937‑wmm770.jpg[0]'
Command :: convert '/var/folders/2b/q6z4f1fn58s83fbx77xwsk5h0000gn/T/64ecce8dbf7049731a63696ae4d7933020151207‑39937‑wmm770.jpg[0]' ‑auto‑orient ‑resize "750x750^" '/var/folders/2b/q6z4f1fn58s83fbx77xwsk5h0000gn/T/a802cd21677cc830b7ba993a8ff7edd920151207‑39937‑1p9h15m'
Command :: identify ‑format '%wx%h,%[exif:orientation]' '/var/folders/2b/q6z4f1fn58s83fbx77xwsk5h0000gn/T/64ecce8dbf7049731a63696ae4d7933020151207‑39937‑wmm770.jpg[0]' 2>/dev/null
Command :: identify ‑format %m '/var/folders/2b/q6z4f1fn58s83fbx77xwsk5h0000gn/T/64ecce8dbf7049731a63696ae4d7933020151207‑39937‑wmm770.jpg[0]'
Command :: convert '/var/folders/2b/q6z4f1fn58s83fbx77xwsk5h0000gn/T/64ecce8dbf7049731a63696ae4d7933020151207‑39937‑wmm770.jpg[0]' ‑auto‑orient ‑resize "600x600>" '/var/folders/2b/q6z4f1fn58s83fbx77xwsk5h0000gn/T/a802cd21677cc830b7ba993a8ff7edd920151207‑39937‑r4bxgl'
Command :: identify ‑format '%wx%h,%[exif:orientation]' '/var/folders/2b/q6z4f1fn58s83fbx77xwsk5h0000gn/T/64ecce8dbf7049731a63696ae4d7933020151207‑39937‑wmm770.jpg[0]' 2>/dev/null
Command :: identify ‑format %m '/var/folders/2b/q6z4f1fn58s83fbx77xwsk5h0000gn/T/64ecce8dbf7049731a63696ae4d7933020151207‑39937‑wmm770.jpg[0]'
Command :: convert '/var/folders/2b/q6z4f1fn58s83fbx77xwsk5h0000gn/T/64ecce8dbf7049731a63696ae4d7933020151207‑39937‑wmm770.jpg[0]' ‑auto‑orient ‑resize "100x100>" '/var/folders/2b/q6z4f1fn58s83fbx77xwsk5h0000gn/T/a802cd21677cc830b7ba993a8ff7edd920151207‑39937‑4zvubq'
Command :: file ‑b ‑‑mime '/var/folders/2b/q6z4f1fn58s83fbx77xwsk5h0000gn/T/64ecce8dbf7049731a63696ae4d7933020151207‑39937‑19vrckc.jpg'

這可能是由字段名稱引起的？還有其他想法嗎？

編輯我的課程模型實際上有點複雜，因為它使用共享表來區分內容類型：

class Lesson < ActiveRecord::Base
  self.table_name = 'steps'
  default_scope { where(content_type: name) }
  has_attached_file :cover_image, styles: { large: "750x750^", medium: "600x600>", thumb: "100x100>" }, default_url: ":style/missing.gif"
  validates_attachment_content_type :cover_image, content_type: /\Aimage\/.*\Z/

  validates :title, presence: true, length: { maximum: 255 }

  def self.create_for_course(course, attributes = {})
    content = new(attributes)
    if content.valid?
      step = Step.create(content_type: name, course: course)
      instance = step.becomes(self)
      instance.update_attributes(attributes)
      instance
    else
      step = content.becomes(Step)
      step.course = course
      step.content_type = name
      step.becomes(self)
    end
  end
  #include Content
  #restrict_attrs :title, :content_body, :cover_image_file_name, :cover_image_content_type, :cover_image_file_size, :cover_image_updated_at, :cover_image

end

參考解法

方法 1:

This was too long for a comment; you'll benefit from using the paperclip_defaults option:

#config/application.rb
...
config.paperclip_defaults = {
   styles: { large: "750x750^", medium: "600x600>", thumb: "100x100>" },     
   default_url: ":style/missing.gif"
} 

This will allow you to just call the attachment name in your models and override the defaults if you so wish:

#app/models/post.rb
class Post < ActiveRecord::Base
  has_attached_file :cover_image
  validates_attachment_content_type :cover_image, content_type: /\Aimage\/.*\Z/
end

‑‑

In respect to your error, I'm not sure what the problem might be.

I have a suggestion though. It's a little tricky, but if you can get it working, it makes all your models super dry.

Here's a link:

#app/models/asset.rb
class Asset < ActiveRecord::Base
    #Associations
    ##################
    belongs_to :assetable, polymorphic: true

    #Paperclip
    ##################
    delegate :url, to: :attachment

########################################

    ##################
    #     Methods    #
    ##################
    before_create :dimensions #‑> https://github.com/thoughtbot/paperclip/wiki/Extracting‑image‑dimensions

    #Width & Height
    def dimensions
        return unless image? && has_dimensions?
        self.width  = geometry.width
        self.height = geometry.height
    end

    ########

    private

    #Geometry ‑> https://github.com/galetahub/ckeditor/blob/master/lib/ckeditor/backend/paperclip.rb#L23
    def geometry
        @geometry ||= begin
            file = attachment.respond_to?(:queued_for_write) ? attachment.queued_for_write[:original] : attachment.to_file
            ::Paperclip::Geometry.from_file(file)
        end
    end

    #Image?
    def image?
        image_types = %w(image/jpeg image/png image/gif image/jpg image/pjpeg image/tiff image/x‑png)
        image_types.include? attachment_content_type
    end

    #Dimensions
    def has_dimensions?
        respond_to?(:width) && respond_to?(:height)
    end
end

Assets table:

This can then be used with STI's:

#app/models/post.rb
class Post < ActiveRecord::Base
    has_one :cover, class_name: "Post::Cover", as: :assetable, dependent: :destroy
    accepts_nested_attributes_for :cover, reject_if: :all_blank
   has
end

#app/models/post/cover.rb
class Post::Cover < Asset
   has_attached_file :attachment
end

This allows you to set the cover attribute as a nested association, but will have the added benefit of storing all the assets in your App in the assets table:

‑‑

Update

You could use the following to make your create_for_course method DRYer:

#app/models/post.rb
class Lesson < ActiveRecord::Base
   attr_reader :course

   belongs_to :step
   before_create :set_step, if Proc.new { |a| a.course }

   private

   def set_step
      self.step.create(course: course) #‑> we can use the course virtual attribute)
   end
end 

Although I doubt it catches your functionality specifically, it would allow you to run:

lesson = Lesson.create course: "5"
# automatically creates "step" with course of "5" and current lesson

(by bo‑oz、Richard Peck)

參考文件

1. Paperclip is not storing alternative sizes for one model, but does for another (CC BY‑SA 2.5/3.0/4.0)