条件转换选项回形针
经过一些研究，我能够根据我的image_class列添加样式。
Model.rb
has_attached_file :image, :styles => lambda { |attachment| attachment.instance.decide_styles } def decide_styles styles = {} case self.image_class when "poster" styles[:thumb] = ["30x45!", :jpg] styles[:standard] = ["185x278!", :jpg] styles[:expanded] = ["372x559!", :jpg] styles[:big] = ["600x900!", :jpg] when "cover" styles[:thumb] = ["30x45!", :jpg] styles[:standard] = ["300x1200!", :jpg] end styles end
这很顺利，现在我也想添加条件convert_options 。 这种方式失败了。
has_attached_file :image, :styles => lambda { |attachment| attachment.instance.decide_styles }, :convert_options => lambda { |attachment| attachment.instance.decide_convert_options } def decide_styles ... end def decide_convert_options opshunz = {} case self.image_class when "poster" opshunz[:thumb] = "-flop" opshunz[:standard] = "-flop" opshunz[:expanded] = "-flop" opshunz[:big] = "-flop" when "cover" opshunz[:thumb] = "-enhance" opshunz[:standard] = "-enhance" end opshunz end
错误：
NoMethodError: undefined method `instance' for :all:Symbol from /Users/AnsPoluke/Sites/nulike/app/models/movie_image.rb:8:in `block in ' from /Users/AnsPoluke/.rvm/gems/ruby-2.1.0/gems/paperclip-4.1.1/lib/paperclip/attachment.rb:431:in `[]' from /Users/AnsPoluke/.rvm/gems/ruby-2.1.0/gems/paperclip-4.1.1/lib/paperclip/attachment.rb:431:in `process_options' from /Users/AnsPoluke/.rvm/gems/ruby-2.1.0/gems/paperclip-4.1.1/lib/paperclip/attachment.rb:423:in `extra_options_for' from /Users/AnsPoluke/.rvm/gems/ruby-2.1.0/gems/paperclip-4.1.1/lib/paperclip/style.rb:56:in `convert_options' from /Users/AnsPoluke/.rvm/gems/ruby-2.1.0/gems/paperclip-4.1.1/lib/paperclip/style.rb:79:in `block in processor_options' from /Users/AnsPoluke/.rvm/gems/ruby-2.1.0/gems/paperclip-4.1.1/lib/paperclip/style.rb:78:in `each' from /Users/AnsPoluke/.rvm/gems/ruby-2.1.0/gems/paperclip-4.1.1/lib/paperclip/style.rb:78:in `processor_options' from /Users/AnsPoluke/.rvm/gems/ruby-2.1.0/gems/paperclip-4.1.1/lib/paperclip/attachment.rb:462:in `block in post_process_style' from /Users/AnsPoluke/.rvm/gems/ruby-2.1.0/gems/paperclip-4.1.1/lib/paperclip/attachment.rb:461:in `each' from /Users/AnsPoluke/.rvm/gems/ruby-2.1.0/gems/paperclip-4.1.1/lib/paperclip/attachment.rb:461:in `inject' from /Users/AnsPoluke/.rvm/gems/ruby-2.1.0/gems/paperclip-4.1.1/lib/paperclip/attachment.rb:461:in `post_process_style' from /Users/AnsPoluke/.rvm/gems/ruby-2.1.0/gems/paperclip-4.1.1/lib/paperclip/attachment.rb:454:in `block in post_process_styles' from /Users/AnsPoluke/.rvm/gems/ruby-2.1.0/gems/paperclip-4.1.1/lib/paperclip/attachment.rb:453:in `each' from /Users/AnsPoluke/.rvm/gems/ruby-2.1.0/gems/paperclip-4.1.1/lib/paperclip/attachment.rb:453:in `post_process_styles' from /Users/AnsPoluke/.rvm/gems/ruby-2.1.0/gems/paperclip-4.1.1/lib/paperclip/attachment.rb:445:in `block (2 levels) in post_process' from /Users/AnsPoluke/.rvm/gems/ruby-2.1.0/gems/activesupport-4.0.2/lib/active_support/callbacks.rb:393:in `_run__3861360263242897910__image_post_process__callbacks' from /Users/AnsPoluke/.rvm/gems/ruby-2.1.0/gems/activesupport-4.0.2/lib/active_support/callbacks.rb:80:in `run_callbacks' from /Users/AnsPoluke/.rvm/gems/ruby-2.1.0/gems/paperclip-4.1.1/lib/paperclip/callbacks.rb:36:in `run_paperclip_callbacks' from /Users/AnsPoluke/.rvm/gems/ruby-2.1.0/gems/paperclip-4.1.1/lib/paperclip/attachment.rb:443:in `block in post_process' from /Users/AnsPoluke/.rvm/gems/ruby-2.1.0/gems/activesupport-4.0.2/lib/active_support/callbacks.rb:383:in `_run__3861360263242897910__post_process__callbacks' from /Users/AnsPoluke/.rvm/gems/ruby-2.1.0/gems/activesupport-4.0.2/lib/active_support/callbacks.rb:80:in `run_callbacks' from /Users/AnsPoluke/.rvm/gems/ruby-2.1.0/gems/paperclip-4.1.1/lib/paperclip/callbacks.rb:36:in `run_paperclip_callbacks' from /Users/AnsPoluke/.rvm/gems/ruby-2.1.0/gems/paperclip-4.1.1/lib/paperclip/attachment.rb:442:in `post_process' from /Users/AnsPoluke/.rvm/gems/ruby-2.1.0/gems/paperclip-4.1.1/lib/paperclip/attachment.rb:114:in `assign' from /Users/AnsPoluke/.rvm/gems/ruby-2.1.0/gems/paperclip-4.1.1/lib/paperclip/has_attached_file.rb:66:in `block in define_setter' from (irb):2 from /Users/AnsPoluke/.rvm/gems/ruby-2.1.0/gems/railties-4.0.2/lib/rails/commands/console.rb:90:in `start' from /Users/AnsPoluke/.rvm/gems/ruby-2.1.0/gems/railties-4.0.2/lib/rails/commands/console.rb:9:in `start' from /Users/AnsPoluke/.rvm/gems/ruby-2.1.0/gems/railties-4.0.2/lib/rails/commands.rb:62:in `' from bin/rails:4:in `require'
任何想法为什么它与styles完美配合但转换失败？
注意：尚未validation工作代码
似乎传入块的参数：convert_options已经是一个实例，而不是附件（而不是样式选项，它是附件）
尝试：
convert_options: lambda { |instance| instance.decide_convert_options }
如果你提取配置数据，你的代码看起来会好一些，例如：
has_attached_file :image, styles: lambda { |attachment| attachment.instance.image_options[:styles] }, convert_options: lambda { |instance| instance.image_options[:convert_options] } IMAGE_OPTIONS = { poster: { styles: { thumb: ["30x45!", :jpg], standard: ["185x278!", :jpg], expanded: ["372x559!", :jpg] big: ["600x900!", :jpg] }, convert_options: { thumb: "-flop", standard: "-flop", expanded: "-flop", big: = "-flop" } }, cover: { styles: { thumb: ["30x45!", :jpg], standard: ["300x1200!", :jpg] }, convert_options: { thumb: "-enhance", standard: "-enhance" } } } def image_options IMAGE_OPTIONS[self.image_class] end
我希望有所帮助
更新：
看起来你的convert_options没有在这里设置： https ： //github.com/thoughtbot/paperclip/blob/a93dfc773b4fd649db4d1281b42a2a71b1ae72ff/lib/paperclip/style.rb#L55
看起来他们建议传递带有样式的convert_options，如本规范： https ： //github.com/thoughtbot/paperclip/blob/263a498195d47563a6227be18cf4463c4c6e7903/spec/paperclip/style_spec.rb#L41
你能试试吗？ 所以完全删除convert_options，并在您的配置中返回哈希，如：
IMAGE_OPTIONS = { poster: { styles: { thumb: { geometry: "30x45!", format: :jpg, convert_options: '-flop', }, standard: {...} expanded: {...} big: {...} } }, cover: { styles: {...}
将它应用于所有人，因为那是你正在做的事情吗？
:convert_options => {:all => "-flop"}
没有你可能正在考虑创建一个Paperclip处理器
批准的答案不起作用。 它可以在评论中阅读，作者承认它尚未在代码中进行测试。
这段代码确实有效：
has_attached_file :image, :styles => lambda { |attachment| thumb_convert_options = case attachment.instance.image_class when "poster" "-flop" when "cover" "-enhance" end { thumb: { convert_options: thumb_convert_options } } }
正确的方法是在styles lambda中使用convert_options ; 将它作为单独的lambda不起作用，至少对于Paperclip 4.1及更高版本。
为了在一个地方保留我的答案，我已将所有代码内联并省略了thumb旁边的所有样式。 显然要实现这个，你应该保留方法decide_convert_options 。
将convert_options添加到样式中。 下面是一个通用rails图像模型的示例，它包含两个样式和相应的布尔值以启用这些样式。
# == Schema Information # # Table name: images # # id :integer not null, primary key # image_file_name :string(255) # image_content_type :string(255) # image_file_size :integer # hero_style :boolean # thumb_style :boolean # image_updated_at :datetime # created_at :datetime not null # updated_at :datetime not null # class Image < ActiveRecord::Base # These are the postprocessing options. # The boolean _style? attributes controls which styles are created. STYLES = { hero: {geometry: "2500x800#", convert_options: "-quality 75 -strip", source_file_options: ""}, thumb: {geometry: "312x100#", convert_options: "-quality 75 -strip", source_file_options: ""} } has_attached_file :image, styles: lambda { |file| r = {} STYLES.keys.each do |stylename| r[stylename] = STYLES[stylename] if file.instance.method("%s_style?" % stylename).call end return r } validates_attachment :image, :presence => true, content_type: { content_type: ["image/jpeg", "image/png"] }, file_name: {matches: [/png\Z/, /jpe?g\Z/]} end