Question

Given the variable content_type = "application/pdf" that can also include any other mime type.

How can I get the default extension for the content type?

I have currently two solutions, which seem very “complicated”.

Hack the string

content_type.split("/")[1]

Use MIME::Types

  require 'mime/types'
  MIME::Types[content_type].first.extensions.first 

Is there a better solution?

Answer 1

Your second solution with the mime type is the solution, which you should choose. There are several reasons for that:

• The second solution is exactly designed for your use case
• Hack the string could be inconsistent or return unexpected results (think about application/postscript has the extension eps!)
• Please consider, that we probably can’t say, that every mime type has it’s default extension. For example: who has defined the default extension for jpg (or jpeg or JPG..) images?