carrierwave

https://github.com/carrierwaveuploader/carrierwave

Ruby

Classier solution for file uploads for Rails, Sinatra and other Ruby web frameworks

CarrierWave::Uploader::MagicMimeBlacklist#blacklist_mime_type_pattern

Override this method in your uploader to provide a black list pattern (regexp)
of content-types which are prohibited to be uploaded.
Compares the file's content-type.

=== Returns

[Regexp] a black list regexp to match the content_type

=== Examples

    def blacklist_mime_type_pattern
      /(text|application)\/json/
    end

Source | Google | Stack overflow

Edit

git clone [email protected]:carrierwaveuploader/carrierwave.git

cd carrierwave

open lib/carrierwave/uploader/magic_mime_blacklist.rb

Contribute

# Make a new branch

git checkout -b -your-name--update-docs-CarrierWave--Uploader--MagicMimeBlacklist-blacklist_mime_type_pattern-for-pr

# Commit to git

git add lib/carrierwave/uploader/magic_mime_blacklist.rbgit commit -m "better docs for CarrierWave::Uploader::MagicMimeBlacklist#blacklist_mime_type_pattern"

# Open pull request

gem install hub # on a mac you can `brew install hub`

hub fork

git push <your name> -your-name--update-docs-CarrierWave--Uploader--MagicMimeBlacklist-blacklist_mime_type_pattern-for-pr

hub pull-request

# Celebrate!