Ruby-on-rails Rails 如何在不出错的情况下删除文件
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Rails how to delete a file without failing on error
提问by AnApprentice
I'm using JPEGCAM to allow users to take a profile pic with their web cam. This uploads a temporary file as so:
我正在使用 JPEGCAM 来允许用户使用他们的网络摄像头拍摄个人资料照片。这会上传一个临时文件，如下所示：
def ajax_photo_upload
File.open(upload_path, 'w:ASCII-8BIT') do |f|
f.write request.raw_post
end
# @user.photo = File.open(upload_path)
@user.assign_attributes(
:photo => File.open(upload_path),
:orig_filename => "#{current_user.full_name}.jpg"
)
if @user.save
respond_to do |format|
.....
private
def upload_path # is used in upload and create
file_name = session[:session_id].to_s + '.jpg'
File.join(::Rails.root.to_s, 'public', 'temp', file_name)
end
What's the best way to go about deleting this temporary file safely? Thanks
安全删除此临时文件的最佳方法是什么？谢谢
回答by severin
When you know that you are done with the file:
当您知道您已完成该文件时：
File.delete(path_to_file) if File.exist?(path_to_file)
Another thing: make sure that you always close files that you have opened, an operating system can only handle a certain number of open files/file descriptors and you'll may run into strange bugs when you pass that limit... So when you want to open files in Ruby always either use the block form:
另一件事：确保你总是关闭你打开的文件，操作系统只能处理一定数量的打开文件/文件描述符，当你超过这个限制时，你可能会遇到奇怪的错误......所以当你想要在 Ruby 中打开文件总是使用块形式：
File.open(path) do |f|
# ...
end
and Ruby will close the file automatically for you. If the block form is not usable, you have to close files by yourself:
Ruby 会自动为你关闭文件。如果块表单不可用，则必须自己关闭文件：
f = File.open(path)
# ...
f.close
So make sure to close the file that you pass to @user.assign_attributes(...)...
所以一定要关闭你传递给的文件@user.assign_attributes(...)......
回答by Andrew Kuklewicz
If you are sure you are done with it, why not just use FileUtils.rmor FileUtils.rm_f?
如果你确定你已经完成了，为什么不直接使用FileUtils.rmorFileUtils.rm_f呢？
FileUtils.rm_f(upload_path)
FileUtils.rm_f(upload_path)
http://www.ruby-doc.org/stdlib-1.9.3/libdoc/fileutils/rdoc/FileUtils.html#method-c-rm_f
http://www.ruby-doc.org/stdlib-1.9.3/libdoc/fileutils/rdoc/FileUtils.html#method-c-rm_f
You could also ignore this in Rails, and have a cron that wakes up and deletes files older than a day from the temp directory that match these temp files. That has the benefit of some margin for error if a file fails to be reprocessed - you don't rm it immediately - and the file operation is not done on the request/response loop for Rails, which will then respond a bit faster.
您也可以在 Rails 中忽略这一点，并使用一个 cron 唤醒并从与这些临时文件匹配的临时目录中删除超过一天的文件。如果文件无法重新处理 - 您不会立即 rm 它 - 并且文件操作不会在 Rails 的请求/响应循环上完成，那么它的好处是有一定的错误余量，然后会更快地响应。
