Rails 4.2, Paperclip gem. Failing to attach .docx type, reads content_type as 'application/zip' despite MIME type being registered

Question

I've registered a MIME Type to allow Paperclip to read a .docx file's content_type as application/vnd.openxmlformats-officedocument.wordprocessingml.document.

However in tests the content_type is still being read as application/zip.

Any idea why? To make things more frustrating, the .pptx and .xlsx mime types have been registered, those tests pass (urgh).

config/initializers/mime_types.rb

Mime::Type.register 'application/vnd.openxmlformats-officedocument.wordprocessingml.document', :docx
Mime::Type.register 'application/vnd.openxmlformats-officedocument.presentationml.presentation', :pptx
Mime::Type.register 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet', :xlsx

app/models/attachment.rb

class Attachment < ActiveRecord::Base
  include FormatFile

  # Constants:
  VALID_FILE_NAMES = [/[^a-z0-9\-]+/i].freeze
  VALID_IMAGE_TYPES = %w[image/jpeg image/jpg image/png image/x-icon image/bnp].freeze
  VALID_CONTENT_TYPES = %w[
    image/jpeg
    image/jpg
    image/gif
    image/png
    image/bmp
    image/x-icon
    text/plain
    text/csv
    application/xml
    application/pdf
    application/msword
    application/vnd.openxmlformats-officedocument.wordprocessingml.document
    application/vnd.openxmlformats-officedocument.wordprocessingml.template
    application/vnd.ms-word.document.macroEnabled.12
    application/vnd.ms-word.template.macroEnabled.12
    application/vnd.ms-excel
    application/vnd.openxmlformats-officedocument.spreadsheetml.sheet
    application/vnd.openxmlformats-officedocument.spreadsheetml.template
    application/vnd.ms-excel.sheet.macroEnabled.12
    application/vnd.ms-excel.template.macroEnabled.12
    application/vnd.ms-excel.addin.macroEnabled.12
    application/vnd.ms-excel.sheet.binary.macroEnabled.12
    application/vnd.ms-powerpoint
    application/vnd.openxmlformats-officedocument.presentationml.presentation
    application/vnd.openxmlformats-officedocument.presentationml.template
    application/vnd.openxmlformats-officedocument.presentationml.slideshow
    application/vnd.ms-powerpoint.addin.macroEnabled.12
    application/vnd.ms-powerpoint.presentation.macroEnabled.12
    application/vnd.ms-powerpoint.template.macroEnabled.12
    application/vnd.ms-powerpoint.slideshow.macroEnabled.12
  ].freeze

  # Associations:
  belongs_to :attachable, polymorphic: true

  # Paperclip attachments
  has_attached_file :attachment,
                    styles:      {
                      medium:   ['300x300#', :png],
                      thumb:    ['100x100#', :png],
                      original: ['500x500>', :png]
                    },
                    default_url: '/images/:style/missing.png',
                    url:         '/system/:class/:attachment/:id_partition/:style/:hash.:extension',
                    path:        ':rails_root/public:url',
                    hash_secret: '623629947a471569fe9808ab386f6e866abde5f582485beaa24fa12032b28a21b6ee94c018fe531484bb438a7376d4a00b4bc35598de34c01f0e40b1dbb37df5'

  # Validations:
  validates_attachment  :attachment,
                        content_type: {content_type: VALID_CONTENT_TYPES},
                        file_name:    {matches: VALID_FILE_NAMES},
                        size:         {in: 0..5.megabytes}
  validates_with AttachmentPresenceValidator, attributes: :attachment

  # Callbacks:
  before_post_process :skip_all_non_images
  before_validation do
    sanitize_filename attachment_file_name
  end

  # Don't shrink and create different styles for anything which isn't an image
  def skip_all_non_images
    VALID_IMAGE_TYPES.include?(attachment_content_type)
  end
end

Thanks for the help.

Edit:

As per the link provided by bkunzi01 I tried the following code. It had no effect, .docx files still fail validation whilst .pptx and .xlsx pass.

config/application.rb

  Paperclip.options[:content_type_mappings] = {
      docx: 'application/vnd.openxmlformats-officedocument.wordprocessingml.document',
      pptx: 'application/vnd.openxmlformats-officedocument.presentationml.presentation',
      xlsx: 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet'
    }

Answer 1

It appears that the new version of paperclip was causing this issue. Downgrading to version 4.3.1 should resolve your issue