我正在进行的网站正在进行重新设计，因此我们的用户图片需要重新调整大小。该网站目前正在使用carrierwave gem处理所有图像和视频处理，每个图像都有一个原始文件，其文件名基于以下内容：
def filename
if original_filename
if model && model.read_attribute(:user_image).present?
model.read_attribute(:user_image)
else
@name ||= "#{secure_token}.#{file.extension}" if original_filename.present?
end
end
end
和secure_token由
生成def secure_token
var = :"@#{mounted_as}_secure_token"
model.instance_variable_get(var) or model.instance_variable_set(var, SecureRandom.uuid)
end
为此而创建的任务是：
##
# CarrierWave Amazon S3 File Reprocessor Rake Task
#
# Written (specifically) for:
# - CarrierWave
# - Ruby on Rails 3
# - Amazon S3
#
# Works with:
# - Any server of which you have write-permissions in the Rails.root/tmp directory
# - Works with Heroku
#
# Not tested with, but might work with:
# - Ruby on Rails 2
#
# Might work with, after a couple of tweaks:
# - File System Storage
# - Cloud Files Storage
# - GridFS
#
# Examples:
#
# Reprocess all versions of User#avatar
# rake carrierwave:reprocess class=User mounted_uploader=avatar
#
# Reprocess the versions: thumb, small, medium for User#avatar
# rake carrierwave:reprocess class=User mounted_uploader=avatar versions='thumb, small, medium'
#
# Reprocess for an underlying association, for things like Embedded MongoDB Documents
# which are models you cannot access directly, but rather through a regular Document
#
# Embeds One (picture) Association
# rake carrierwave:reprocess class=User association=picture mounted_uploader=image versions='thumb, small, medium'
#
# Embeds Many (pictures) Association
# rake carrierwave:reprocess class=User association=pictures mounted_uploader=image versions='thumb, small, medium'
#
# WARNING
# There is an issue with "Rake", that you cannot name your mounted_uploader "file".
# If you do this, then you will not be able to reprocess images through this rake task
# class User
# include Mongoid::Document
# mount_uploader :file, PictureUploader
# end
#
# This will NOT work with reprocessing through Rake because the mounted_uploader uses the "file" attribute.
namespace :carrierwave do
##
# Only tested with Amazon S3 Storage
# Needs some minor modifications if you want to use this for File System Store, Cloud Files and GridFS probably.
# This should work without Ruby on Rails as well, just set a different TMP_PATH.
desc "Reprocesses Carrier Wave file versions of a given model."
task :reprocess => :environment do
##
# Load in the OPEN URI library to be able
# to pull down and store the original file in a temp directory
require 'open-uri'
##
# Default constants
TMP_PATH = "#{Rails.root}/tmp/carrierwave"
##
# Set environment constants
CLASS = ENV['class'].capitalize
ASSOCIATION = ENV['association'] || nil
MOUNTED_UPLOADER = ENV['mounted_uploader'].to_sym
VERSIONS = ENV['versions'].nil? ? Array.new : ENV['versions'].split(',').map {|version| version.strip.to_sym}
##
# Find the Model
MODEL = Kernel.const_get(CLASS)
##
# Create the temp directory
%x(mkdir -p "#{TMP_PATH}")
##
# Find all records for the provided Model
records = MODEL.all
##
# Output to console
puts "\nCarrier Wave Version Reprocessing!"
puts "======================================="
puts "Model: #{CLASS}"
puts "Mounted Uploader: #{MOUNTED_UPLOADER}"
puts "Association: #{ASSOCIATION}" if ASSOCIATION
puts "Versions: #{VERSIONS.empty? ? "all" : VERSIONS.join(', ')}\n\n"
##
# Run through all records
records.each do |record|
##
# Set the mounted uploader object
# If it has a one-to-one association (singular) then that object
# will be returned and wrapped in an array so we can "iterate" through it below.
#
# If it has a one-to-many association then it will return the array of associated objects
#
# If no association is specified, it assumes the amounted uploader is attached to the specified CLASS
if ASSOCIATION
if ASSOCIATION.singular?
objects = [record.send(ASSOCIATION)]
else
objects = record.send(ASSOCIATION)
end
else
objects = [record]
end
##
# Iterates through the objects
objects.each do |object|
##
# Returns the mounted uploader object
mounted_object = object.send(MOUNTED_UPLOADER)
##
# Retrieve Filename
filename = mounted_object.path.split('/').last
##
# Output to console
puts "Reprocessing: #{filename}"
##
# Read out the original file from the remote location
# and write it out to the temp directory (TMP_PATH)
# This file will be used as the base file to reprocess
# the versions. Once all versions have been processed,
# this temp file will be directly removed.
open(mounted_object.url) do |original_object|
File.open(File.join(TMP_PATH, filename), 'w') do |temp_file|
temp_file.write(original_object.read)
end
end
##
# By default it will add all available versions to the versions variable
# which means that all available versions will be reprocessed.
# If the "versions" argument has been provided, then only the specified
# version(s) will be set to the versions variable, and thus, only these
# will be reprocessed.
versions = mounted_object.versions.map {|version| version[0]}
versions = VERSIONS unless VERSIONS.empty?
##
# Reprocesses the versions
versions.each do |version|
mounted_object.send(version).cache!(File.open(File.join(TMP_PATH, filename)))
mounted_object.send(version).store!
end
##
# Removes the temp file
%x(rm "#{TMP_PATH}/#{filename}")
end
end
end
end
问题在于，当它创建新图像时，文件以新文件名保存，而不是遵循图像上传器中列出的命名，因此网站无法找到它们。以下是如何存储图像的示例。
应该如何：
原始档案： fdk392ks93_39ei.png
缩略图版本： thumb_fdk392ks93_39ei.png
它是怎么回事：
原始档案： fdk392ks93_39ei.png
缩略图版本： thumb_fajeilkadifej_jakdjfi.png
非常感谢任何帮助。
其他信息：
模特：用户
Uploader：user_image（这也是存储文件夹/文件名的列名）
答案 0 :(得分：17)
致电recreate_versions!后，您必须在模特上致电save!。您可以查看this question，其中有人问基本相同的事情。
答案 1 :(得分：9)
README清楚地说明了如何重新创建Carrierwave版本：
https://github.com/jnicklas/carrierwave/blob/master/README.md
“您可能会遇到想要追溯更改版本或添加新版本的情况。您可以使用recreate_versions！方法从基础文件重新创建版本。这使用了一种天真的方法，可以重新上传如果没有作为参数传递，则处理指定的版本或所有版本。
instance = MyUploader.new
instance.recreate_versions!(:thumb, :large)
或者在装载的上传器上：
User.all.each do |user|
user.avatar.recreate_versions!
end