我正在尝试将图像保存到Redis,稍后将在Resque任务中获取并上传到我们的图像服务器。
ImageHandle类将为我们获取图像。目前,我只关心在Redis中获取图像。
class ImageHandle < ActiveRecord::Base
attr_accessible :uploaded, :image
after_save :save_image
def image_data
$redis.get(redis_key)
end
def image=(value)
@image = value
end
private
def redis_key
@redis_key ||= "image_handle:#{id}:image"
end
def save_image
$redis.set(redis_key, @image.read)
end
end
其中$redis是在初始化器中设置的:
$redis = Redis.new
这是我的测试文件:
require 'test_helper'
class ImageHandleTest < ActiveSupport::TestCase
include ActionDispatch::TestProcess
setup do
clear_redis
end
test 'saves an image' do
image = fixture_file_upload('screaming-eagle.jpg', 'image/jpg')
# You can only read from a file fixture once
same_image = fixture_file_upload('screaming-eagle.jpg', 'image/jpg')
image_handle = ImageHandle.create(image: image)
expected = same_image.read
actual = image_handle.image_data
puts "length of expected: #{expected.length}"
puts "length of actual: #{actual.length}"
assert_equal expected, actual
end
end
结果是:
length of expected: 81500
length of actual: 78524
F
Finished tests in 0.270385s, 3.6984 tests/s, 3.6984 assertions/s.
1) Failure:
test_saves_an_image:23
我不知道发生了什么事。
当我尝试设置("b"*81500)然后获取它时,我将它恢复到预期的81500长度。
谢谢你能给我的任何帮助。
redis-rb将字符串转换为默认的外部编码,该编码由Encoding::default_external
定义,通常为UTF-8。看见https://github.com/redis/redis-rb/commit/61fa1f884a643cd7dea8e0e56498860594058a39
您可以在存储二进制数据之前将其编码为Base64,并在检索后从Base64解码:
class ImageHandle < ActiveRecord::Base
attr_accessible :uploaded, :image
after_save :save_image
def image_data
Base64.decode $redis.get(redis_key)
end
def image=(value)
@image = value
end
private
def redis_key
@redis_key ||= "image_handle:#{id}:image"
end
def save_image
$redis.set redis_key, Base64.encode(@image.read)
end
end
您可以在不丢失数据的情况下将字符串转换为ASCII-8BIT。更新此方法:
def image_data
$redis.get(redis_key).force_encoding(Encoding::ASCII_8BIT)
end
它比Base64更快、更简单。