在 Ruby 中查找文件名的扩展名
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Find the extension of a filename in Ruby
提问by Bryan Cosgrove
I'm working on the file upload portion of a Rails app. Different types of files are handled differently by the app.
我正在处理 Rails 应用程序的文件上传部分。应用程序以不同方式处理不同类型的文件。
I want to make a whitelist of certain file extensions to check the uploaded files against to see where they should go. All of the file names are strings.
我想制作某些文件扩展名的白名单，以检查上传的文件以查看它们应该去哪里。所有文件名都是字符串。
I need a way to check only the extension part of the file name string. The file names are all in the format of "some_file_name.some_extension".
我需要一种方法来只检查文件名字符串的扩展名部分。文件名都是“some_file_name.some_extension”格式。
回答by Felix
That's really basic stuff:
这真的是基本的东西：
irb(main):002:0> accepted_formats = [".txt", ".pdf"]
=> [".txt", ".pdf"]
irb(main):003:0> File.extname("example.pdf") # get the extension
=> ".pdf"
irb(main):004:0> accepted_formats.include? File.extname("example.pdf")
=> true
irb(main):005:0> accepted_formats.include? File.extname("example.txt")
=> true
irb(main):006:0> accepted_formats.include? File.extname("example.png")
=> false
回答by megas
Use extnamemethod from File class
使用extnameFile 类中的方法
File.extname("test.rb") #=> ".rb"
Also you may need basenamemethod
你也可能需要basename方法
File.basename("/home/gumby/work/ruby.rb", ".rb") #=> "ruby"
回答by gertas
Quite old topic but here is the way to get rid of extension separator dot and possible trailing spaces:
很老的话题，但这里是摆脱扩展分隔符点和可能的尾随空格的方法：
File.extname(path).strip.downcase[1..-1]
Examples:
例子：
File.extname(".test").strip.downcase[1..-1] # => nil
File.extname(".test.").strip.downcase[1..-1] # => nil
File.extname(".test.pdf").strip.downcase[1..-1] # => "pdf"
File.extname(".test.pdf ").strip.downcase[1..-1] # => "pdf"
