Ruby on rails 使用RubyZip生成文件并作为zip下载

对于我的RubyonRails项目（Rails版本5.1.2），我正在生成图像文件（png），并使用RubyZip gem将它们作为zipfile下载

图像文件不存储在任何目录中。我有一个模型叫附件。每个附件都有一个属性image_string，它是图像的base64字符串。您可以使用类似于

image\u标记（src=“data:image/jpeg；base64，{attachment.image\u string}”，样式：“border radius:0；”）的标记来显示图像

对于多个图像，我希望为每个图像创建临时文件，而不将它们存储在任何位置，并将这些图像作为zip文件下载

我现在拥有的代码是：

def bulk_download
  require('zip')
  ::Zip::File.open("/tmp/mms.zip", Zip::File::CREATE) do |zipfile|
    Attachment.all.each do |attachment|
      image_file = Tempfile.new("#{attachment.created_at.in_time_zone}.png")
      image_file.write(attachment.image_string)
      zipfile.add("#{attachment.created_at.in_time_zone}.png", image_file.path)
    end
  end
  send_file "/tmp/mms.zip", type: 'application/zip', disposition: 'attachment', filename: "my_archive.zip"
  respond_to do |format |
    format.all { head :ok, content_type: "text/html" }
  end
end

但下载的zipfile中没有文件，大小为0字节。

---

提前感谢。

您应该像这样关闭和取消链接zip文件：

require('zip')

class SomeController < ApplicationController
  # ...

  def bulk_download
    filename = 'my_archive.zip'
    temp_file = Tempfile.new(filename)

    begin
      Zip::OutputStream.open(temp_file) { |zos| }

      Zip::File.open(temp_file.path, Zip::File::CREATE) do |zip|
        Attachment.all.each do |attachment|
          image_file = Tempfile.new("#{attachment.created_at.in_time_zone}.png")
          image_file.write(attachment.image_string)
          zipfile.add("#{attachment.created_at.in_time_zone}.png", image_file.path)
        end
      end

      zip_data = File.read(temp_file.path)
      send_data(zip_data, type: 'application/zip', disposition: 'attachment', filename: filename)
    ensure # important steps below
      temp_file.close
      temp_file.unlink
    end
  end
end

require（'zip'））
类SomeController

以下是我用作此代码源代码的一篇很好的博客文章：

---

此外，最好将所有库要求放在文件的顶部（即

require（'zip'）

）。

公认的解决方案确实是正确的。但是，我将扩展已经提供的解决方案，使其能够与

ActiveStorage

附件一起工作
在使用公认的解决方案时，我发现

image\u string

方法对

ActiveStorage

附件不起作用，并抛出如下错误

NoMethodError - undefined method `image_string' for #<ActiveStorage::Attached::One:0x00007f78cc686298>

为了使ActiveStorage附件能够正常工作，我们需要如下更新代码

begin
  Zip::OutputStream.open(temp_file) { |zos| }

  Zip::File.open(temp_file.path, Zip::File::CREATE) do |zip|
    Product.all.each do |product|
      image_file = Tempfile.new("#{product.attachment.created_at.in_time_zone}.png")
      
    # image_file.write(product.attachment.image_string) #this does not work for ActiveStorage attachments
      
      # use this instead
      File.open(image_file.path, 'w', encoding: 'ASCII-8BIT') do |file|
        product.attachment.download do |chunk|
          file.write(chunk)
        end
      end

      zipfile.add("#{product.attachment.created_at.in_time_zone}.png", image_file.path)
    end
  end

  zip_data = File.read(temp_file.path)
  send_data(zip_data, type: 'application/zip', disposition: 'attachment', filename: filename)

ensure # important steps below
  temp_file.close
  temp_file.unlink
end

---

嘿@jl118，我的答案对你有用吗？

begin
  Zip::OutputStream.open(temp_file) { |zos| }

  Zip::File.open(temp_file.path, Zip::File::CREATE) do |zip|
    Product.all.each do |product|
      image_file = Tempfile.new("#{product.attachment.created_at.in_time_zone}.png")
      
    # image_file.write(product.attachment.image_string) #this does not work for ActiveStorage attachments
      
      # use this instead
      File.open(image_file.path, 'w', encoding: 'ASCII-8BIT') do |file|
        product.attachment.download do |chunk|
          file.write(chunk)
        end
      end

      zipfile.add("#{product.attachment.created_at.in_time_zone}.png", image_file.path)
    end
  end

  zip_data = File.read(temp_file.path)
  send_data(zip_data, type: 'application/zip', disposition: 'attachment', filename: filename)

ensure # important steps below
  temp_file.close
  temp_file.unlink
end