philiprehberger-mime_type

MIME type detection from file extensions and magic bytes with 200+ mappings

Requirements

Ruby >= 3.1

Installation

Add to your Gemfile:

gem "philiprehberger-mime_type"

Or install directly:

gem install philiprehberger-mime_type

Usage

require "philiprehberger/mime_type"

Philiprehberger::MimeType.for_extension('.pdf')   # => "application/pdf"
Philiprehberger::MimeType.for_filename('photo.jpg')  # => "image/jpeg"

Magic Byte Detection

content = File.binread('image.png', 16)
Philiprehberger::MimeType.for_content(content)  # => "image/png"

Modern image formats are also detected via the ISOBMFF ftyp brand: HEIC, HEIF, AVIF, and JPEG XL.

MIME Aliases

require "philiprehberger/mime_type"

Philiprehberger::MimeType.canonical('image/jpg')  # => "image/jpeg"
Philiprehberger::MimeType.valid?('image/jpg')     # => true

Reverse Lookup

Philiprehberger::MimeType.extensions('text/html')  # => [".html", ".htm"]

Validation

Philiprehberger::MimeType.valid?('text/plain')     # => true
Philiprehberger::MimeType.valid?('not valid')      # => false

Custom Registration

Philiprehberger::MimeType.register('.custom', 'application/x-custom')
Philiprehberger::MimeType.for_extension('.custom')  # => "application/x-custom"

Philiprehberger::MimeType.unregister('.custom')
Philiprehberger::MimeType.for_extension('.custom')  # => nil

Charset Detection

Philiprehberger::MimeType.charset('text/html')        # => "utf-8"
Philiprehberger::MimeType.charset('application/json')  # => nil

Type Predicates

Philiprehberger::MimeType.text?('text/plain')       # => true
Philiprehberger::MimeType.binary?('image/png')      # => true

Category Predicates

Philiprehberger::MimeType.image?('image/png')                   # => true
Philiprehberger::MimeType.text?('text/html; charset=utf-8')     # => true
Philiprehberger::MimeType.audio?('audio/mpeg')                  # => true
Philiprehberger::MimeType.video?('video/mp4')                   # => true
Philiprehberger::MimeType.application?('application/json')       # => true
Philiprehberger::MimeType.font?('font/woff2')                   # => true
Philiprehberger::MimeType.multipart?('multipart/form-data')      # => true
Philiprehberger::MimeType.message?('message/rfc822')             # => true
Philiprehberger::MimeType.image?(nil)                           # => false

Accept Header Parsing

Philiprehberger::MimeType.parse_accept('text/html;q=0.9, application/json')
# => [{ type: "application/json", q: 1.0 }, { type: "text/html", q: 0.9 }]

Content Negotiation

available = ['application/json', 'text/html']
Philiprehberger::MimeType.best_match(available, 'text/*;q=0.5, application/json')
# => "application/json"

API

Method	Description
`MimeType.for_extension(ext)`	Detect MIME type from a file extension
`MimeType.for_filename(name)`	Detect MIME type from a filename
`MimeType.for_content(bytes)`	Detect MIME type from magic bytes
`MimeType.extensions(mime)`	Get file extensions for a MIME type
`MimeType.category(mime)`	Get the category of a MIME type
`MimeType.valid?(mime)`	Check if a MIME type string is valid
`MimeType.canonical(mime)`	Map legacy/alias MIME types to their canonical form
`MimeType.register(ext, mime)`	Register a custom MIME type mapping
`MimeType.unregister(ext)`	Remove a custom registration
`MimeType.charset(mime)`	Get default charset for a MIME type
`MimeType.parse_accept(header)`	Parse HTTP Accept header string
`MimeType.best_match(available, header)`	Content negotiation for best match
`MimeType.text?(mime)`	Check if MIME type is text
`MimeType.binary?(mime)`	Check if MIME type is binary
`MimeType.image?(mime)`	Check if MIME type is `image/*`
`MimeType.audio?(mime)`	Check if MIME type is `audio/*`
`MimeType.video?(mime)`	Check if MIME type is `video/*`
`MimeType.application?(mime)`	Check if MIME type is `application/*`
`MimeType.font?(mime)`	Check if MIME type is `font/*`
`MimeType.multipart?(mime)`	Check if MIME type is `multipart/*`
`MimeType.message?(mime)`	Check if MIME type is `message/*`

Development

bundle install
bundle exec rspec
bundle exec rubocop

Support

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License

MIT