我正在使用Rails + ActiveStorage上传图像文件,并希望在上传后在数据库中保存宽度和高度。但是,我在任何地方都找不到此类示例。
这是我从各种API文档中整理而来的内容,但最终出现此错误:0
3
0
。将private method 'open' called for #<String:0x00007f9480610118>
替换为blob
会导致Rails记录“正在跳过图像分析,因为ImageMagick不支持该文件”(https://github.com/rails/rails/blob/master/activestorage/lib/active_storage/analyzer/image_analyzer.rb#L39)。
代码:
image.file
此方法也有问题,因为class Image < ApplicationRecord
after_commit { |image| set_dimensions image }
has_one_attached :file
def set_dimensions(image)
if (image.file.attached?)
blob = image.file.download
# error: private method `open' called for #<String:0x00007f9480610118>
meta = ActiveStorage::Analyzer::ImageAnalyzer.new(blob).metadata
end
end
end
也被称为destroy。
TLDR:是否有“适当”的方式在上传后立即获取图像元数据?
答案 0 :(得分:4)
回答自己的问题:我的原始解决方案已经结束,但是需要安装ImageMagick(不是,并且错误消息没有指出这一点)。这是我的最终代码:
class Image < ApplicationRecord
attr_accessor :skip_set_dimensions
after_commit ({unless: :skip_set_dimensions}) { |image| set_dimensions image }
has_one_attached :file
def set_dimensions(image)
if (Image.exists?(image.id))
if (image.file.attached?)
meta = ActiveStorage::Analyzer::ImageAnalyzer.new(image.file).metadata
image.width = meta[:width]
image.height = meta[:height]
else
image.width = 0
image.height = 0
end
image.skip_set_dimensions = true
image.save!
end
end
end
我还使用this technique跳过了save!
上的回调,以防止无限循环。
答案 1 :(得分:1)
根据ActiveStorage Overview Guild,已经存在使用docs的解决方案image.file.analyze
和image.file.analyze_later
(ActiveStorage::Analyzer::ImageAnalyzer)
首次连接新的Blob时,会通过analyst_later自动进行异步分析。
这意味着您可以通过以下方式访问图像尺寸
image.file.metadata
#=> {"identified"=>true, "width"=>2448, "height"=>3264, "analyzed"=>true}
image.file.metadata['width']
image.file.metadata['height']
因此您的模型可以如下所示:
class Image < ApplicationRecord
has_one_attached :file
def height
file.metadata['height']
end
def width
file.metadata['width']
end
end
在90%的常规情况下,您对此都很满意
但是:问题在于,这是“异步分析”(#analyze_later
),这意味着上传后不会立即存储元数据
image.save!
image.file.metadata
#=> {"identified"=>true}
image.file.analyzed?
# => nil
# .... after ActiveJob for analyze_later finish
image.reload
image.file.analyzed?
# => true
#=> {"identified"=>true, "width"=>2448, "height"=>3264, "analyzed"=>true}
这意味着如果您需要实时访问宽度/高度(例如,新上传文件的尺寸的API响应)
class Image < ApplicationRecord
has_one_attached :file
after_commit :save_dimensions_now
def height
file.metadata['height']
end
def width
file.metadata['width']
end
private
def save_dimensions_now
file.analyze if file.attached?
end
end
注意:在Job中异步完成此操作有充分的理由。由于需要执行额外的代码,因此您的请求响应速度会稍慢。因此,您需要有充分的理由“立即保存尺寸”
此解决方案的镜像位于How to store Image Width Height in Rails ActiveStorage
建议:不要这样做,要依靠现有的Vanilla Rails解决方案
Bogdan Balan's solution将起作用。这是没有skip_set_dimensions
attr_accessor
class Image < ApplicationRecord
after_commit :set_dimensions
has_one_attached :file
private
def set_dimensions
if (file.attached?)
meta = ActiveStorage::Analyzer::ImageAnalyzer.new(file).metadata
height = meta[:height]
width = meta[:width]
else
height = 0
width = 0
end
update_columns(width: width, height: height) # this will save to DB without Rails callbacks
end
end
可能是您正在创建一个想要在其中存储文件附件的模型,而不再对其进行更新。 (因此,如果您需要更新附件,只需创建新的模型记录并删除旧的模型记录即可)
在这种情况下,代码甚至更加流畅:
class Image < ApplicationRecord
after_commit :set_dimensions, on: :create
has_one_attached :file
private
def set_dimensions
meta = ActiveStorage::Analyzer::ImageAnalyzer.new(file).metadata
self.height = meta[:height] || 0
self.width = meta[:width] || 0
save!
end
end
您是否有机会在保存之前验证附件是否存在。您可以使用active_storage_validations gem
class Image < ApplicationRecord
after_commit :set_dimensions, on: :create
has_one_attached :file
# validations by active_storage_validations
validates :file, attached: true,
size: { less_than: 12.megabytes , message: 'image too large' },
content_type: { in: ['image/png', 'image/jpg', 'image/jpeg'], message: 'needs to be an PNG or JPEG image' }
private
def set_dimensions
meta = ActiveStorage::Analyzer::ImageAnalyzer.new(file).metadata
self.height = meta[:height] || 0
self.width = meta[:width] || 0
save!
end
end
测试
require 'rails_helper'
RSpec.describe Image, type: :model do
let(:image) { build :image, file: image_file }
context 'when trying to upload jpg' do
let(:image_file) { FilesTestHelper.jpg } # https://blog.eq8.eu/til/factory-bot-trait-for-active-storange-has_attached.html
it do
expect { image.save }.to change { image.height }.from(nil).to(35)
end
it do
expect { image.save }.to change { image.width }.from(nil).to(37)
end
it 'on update it should not cause infinitte loop' do
image.save! # creates
image.rotation = 90 # whatever change, some random property on Image model
image.save! # updates
# no stack ofverflow happens => good
end
end
context 'when trying to upload pdf' do
let(:image_file) { FilesTestHelper.pdf } # https://blog.eq8.eu/til/factory-bot-trait-for-active-storange-has_attached.html
it do
expect { image.save }.not_to change { image.height }
end
end
end
attaching Active Storange to Factory Bot
中说明了FilesTestHelper.jpg
的工作方式
答案 2 :(得分:-1)
我认为您可以在更新之前从javascript中获取尺寸,然后将这些数据发布到控制器中。 您可以查看一下: Check image width and height before upload with Javascript