ruby-on-rails - 载波 gem 。重新创建后如何重命名上传的图像版本？

Question

我有 RailsCasts 中描述的类似模型:

应用程序/模型/resident.rb:

class Resident < ActiveRecord::Base
  include PhotoConcern
end

应用程序/模型/employee.rb:

class Employee < ActiveRecord::Base
  include PhotoConcern
end

应用程序/模型/关注/photo_concern.rb:

module PhotoConcern
  extend ActiveSupport::Concern

  included do
    mount_uploader :photo, PhotoUploader

    attr_accessor :photo_crop_x, :photo_crop_y, :photo_crop_w, :photo_crop_h

    after_save :crop_photo

    def crop_photo
      photo.recreate_versions! if photo_crop_x.present?
    end
  end
end

应用程序/上传器/photo_uploader.rb:

class PhotoUploader < CarrierWave::Uploader::Base
  include CarrierWave::MiniMagick

  storage :file

  def store_dir
    "uploads/#{model.class.to_s.underscore}/#{mounted_as}/#{model.id}"
  end

  version :cropped do
    process :crop
  end

  version :thumb, from_version: :cropped do
    process resize_to_fill: [100, 100]
  end

  version :avatar, from_version: :cropped do
    process resize_to_fill: [200, 200]
  end

  def crop
    return if model.photo_crop_x.blank?

    resize_to_limit(500, nil)
    resize_to_fit(500, nil)

    manipulate! do |img|
      size = model.photo_crop_w << 'x' << model.photo_crop_h
      offset = '+' << model.photo_crop_x << '+' << model.photo_crop_y

      img.crop("#{size}#{offset}")
      img
    end
  end
end

应用程序/ View /员工/show.slim

= image_tag (@employee.photo.present? ? @employee.photo.url(:avatar) : "client_#{@employee.sex}.png"), class: 'img-circle img-responsive'

我想在裁剪后重命名版本文件，这样我的用户就不会为缓存而苦恼。 CarrierWave wiki 中描述了如何重命名文件以及 it's written “为了保存新生成的文件名，您必须在 recreate_versions 后调用模型上的 save!!”。

如何重命名版本文件？我打不通 save!在我的员工的 after_save再次因为有更多的钩子(Hook)不应该被调用两次。此外，PhotoConcern 包含在另一个类中。

相关维基文章:

How to: Create random and unique filenames for all versioned files

How to: Customize your version file names

How to: Use a timestamp in file names

Answer 1

In order to save the newly generated filename you have to call save! on the model after recreate_versions!.

所以我相信你的疑惑的答案包含在 Carrierwave rubydocumentation中。

recreate_versions!(*versions) ⇒ Object

Recreate versions and reprocess them. This can be used to recreate versions if their parameters somehow have changed.

此方法将存储 *versions如果没有省略，则 cached file将被存储。

# File 'lib/carrierwave/uploader/versions.rb', line 216

def recreate_versions!(*versions)
  # Some files could possibly not be stored on the local disk. This
  # doesn't play nicely with processing. Make sure that we're only
  # processing a cached file
  #
  # The call to store! will trigger the necessary callbacks to both
  # process this version and all sub-versions
  if versions.any?
    file = sanitized_file if !cached?
    # the file will be stored
    store_versions!(file, versions)
  else
    cache! if !cached?
    # If new_file is omitted, a previously cached file will be stored.
    store!
  end

store! 是什么意思做？

这是 the rubydoc page about store!

store!(new_file = nil) ⇒ Object

Stores the file by passing it to this Uploader's storage engine. If new_file is omitted, a previously cached file will be stored

此方法包含在您的 class PhotoUploader < CarrierWave::Uploader::Base 中。它使用 with_callbacks使用回调 :store 存储您的文件.回调触发此方法。

# File 'lib/carrierwave/uploader/store.rb', line 53

def store!(new_file=nil)
  cache!(new_file) if new_file && ((@cache_id != parent_cache_id) || @cache_id.nil?)
  if !cache_only and @file and @cache_id
    with_callbacks(:store, new_file) do
      new_file = storage.store!(@file)
      if delete_tmp_file_after_storage
        @file.delete unless move_to_store
        cache_storage.delete_dir!(cache_path(nil))
      end
      @file = new_file
      @cache_id = nil
    end
  end
end

store_versions! 是什么意思方法呢？

def store_versions!(new_file, versions=nil)
  if versions
    active = Hash[active_versions]
    versions.each { |v| active[v].try(:store!, new_file) } unless active.empty?
  else
    active_versions.each { |name, v| v.store!(new_file) }
  end
end

什么是 Carrierwave 回调以及如何使用它们？

 after :store, :store_versions!

这个问题在 SO explains和 wiki通过 after :store, :my_method 解释回调是如何工作的在您的 version :low do 内 block ，您将执行 my_method仅在 after :store 上回调(仅适用于该版本)。
:store回调对应 store!的执行.

什么是 @filename属性？ recreate_versions!如何编码文件名？
@filename用方法 filename 定义在 lib/carrierwave/uploader/store.rb

##
# Override this in your Uploader to change the filename.
#
# Be careful using record ids as filenames. If the filename is stored in the database
# the record id will be nil when the filename is set. Don't use record ids unless you
# understand this limitation.
#
# Do not use the version_name in the filename, as it will prevent versions from being
# loaded correctly.
#
# === Returns
#
# [String] a filename
#
def filename
  @filename
end

来自carrierwave的指南建议使用 def filename在使用 recreate_version! 重新创建版本时重新创建唯一的文件名.

该方法不保存到数据库，保存到数据库需要调用 save!关于拨款 Carrierwave回调，不会打扰您 Carrierwave gem

我没有这个问题的解决方案，但是没有关于这个的文档，我们应该开始构建它。