Class: Rack::MobileDetect

Inherits:
Object
  • Object
show all
Defined in:
lib/rack/mobile-detect.rb

Overview

Full project at github.com/talison/rack-mobile-detect

Rack::MobileDetect detects mobile devices and adds an X_MOBILE_DEVICE header to the request if a mobile device is detected. The strategy for detecting a mobile device is as follows:

  1. Search for a ‘targeted’ mobile device. A targeted mobile device

is a mobile device you may want to provide special content to because it has advanced capabilities - for example an iPad, iPhone or Android device. Targeted mobile devices are detected via a Regexp applied against the HTTP User-Agent header.

By default, the targeted devices are iPhone, Android, iPad and iPod. If a targeted device is detected, the token match from the regular expression will be the value passed in the X_MOBILE_DEVICE header, i.e.: X_MOBILE_DEVICE: iPhone

  1. Search for a UAProf device. More about UAProf detection can be

found here: www.developershome.com/wap/detection/detection.asp?page=profileHeader

If a UAProf device is detected, the value of X_MOBILE_DEVICE is simply set to ‘true’.

  1. Look at the HTTP Accept header to see if the device accepts WAP

content. More information about this form of detection is found here: www.developershome.com/wap/detection/detection.asp?page=httpHeaders

Any device detected using this method will have X_MOBILE_DEVICE set to ‘true’.

  1. Use a ‘catch-all’ regex. The current catch-all regex was taken

from the mobile-fu project. See: github.com/brendanlim/mobile-fu

Any device detected using this method will have X_MOBILE_DEVICE set to ‘true’.

If none of the detection methods detected a mobile device, the X_MOBILE_DEVICE header will be absent.

Note that Rack::MobileDetect::X_HEADER holds the string ‘X_MOBILE_DEVICE’ that is inserted into the request headers.

Usage: use Rack::MobileDetect

This allows you to do mobile device detection with the defaults.

use Rack::MobileDetect, :targeted => /SCH-w*$|[Bb]lackerryw*/

In this usage you can set the value of the regular expression used to target particular devices. This regular expression captures Blackberry and Samsung SCH-* model phones. For example, if a phone with the user-agent: ‘BlackBerry9000/4.6.0.167 Profile/MIDP-2.0 Configuration/CLDC-1.1 VendorID/102’ connects, the value of X_MOBILE_DEVICE will be set to ‘BlackBerry9000’

use Rack::MobileDetect, :catchall => /mydevice/i

This allows you to limit the catchall expression to only the device list you choose.

See the unit test source code for more info.

Author: Tom Alison (tom.alison at gmail.com) License: MIT

Constant Summary collapse

X_HEADER = 
'X_MOBILE_DEVICE'

Instance Method Summary collapse

Constructor Details

#initialize(app, options = {}) ⇒ MobileDetect

Users can pass in a :targeted option, which should be a Regexp specifying which user-agent agent tokens should be specifically captured and passed along in the X_MOBILE_DEVICE variable.

The :catchall option allows specifying a Regexp to catch mobile devices that fall through the other tests.



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# File 'lib/rack/mobile-detect.rb', line 105

def initialize(app, options = {})
  @app = app

  # @ua_targeted holds a list of user-agent tokens that are
  # captured. Captured tokens are passed through in the
  # environment variable. These are special mobile devices that
  # may have special rendering capabilities for you to target.
  @regex_ua_targeted = options[:targeted] || /iphone|android|ipod|ipad/i

  # Match mobile content in Accept header:
  # http://www.developershome.com/wap/detection/detection.asp?page=httpHeaders
  @regex_accept = /vnd\.wap/i

  # From mobile-fu: http://github.com/brendanlim/mobile-fu
  @regex_ua_catchall = options[:catchall] ||
    Regexp.new('palm|blackberry|nokia|phone|midp|mobi|symbian|chtml|ericsson|minimo|' +
               'audiovox|motorola|samsung|telit|upg1|windows ce|ucweb|astel|plucker|' +
               'x320|x240|j2me|sgh|portable|sprint|docomo|kddi|softbank|android|mmp|' +
               'pdxgw|netfront|xiino|vodafone|portalmmm|sagem|mot-|sie-|ipod|up\\.b|' +
               'webos|amoi|novarra|cdm|alcatel|pocket|ipad|iphone|mobileexplorer|' +
               'mobile', true)

  # A URL that specifies a single redirect-url for any device
  @redirect_to = options[:redirect_to]
  # A mapping of devices to redirect URLs, for targeted devices
  @redirect_map = options[:redirect_map]
end

Instance Method Details

#call(env) ⇒ Object

Because the web app may be multithreaded, this method must create new Regexp instances to ensure thread safety.



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# File 'lib/rack/mobile-detect.rb', line 135

def call(env)
  device = nil
  user_agent = env.fetch('HTTP_USER_AGENT', '')

  # First check for targeted devices and store the device token
  device = Regexp.new(@regex_ua_targeted).match(user_agent)

  # Fall-back on UAProf detection
  # http://www.developershome.com/wap/detection/detection.asp?page=profileHeader
  device ||= env.keys.detect { |k| k.match(/^HTTP(.*)_PROFILE$/) } != nil

  # Fall back to Accept header detection
  device ||= Regexp.new(@regex_accept).match(env.fetch('HTTP_ACCEPT','')) != nil

  # Fall back on catch-all User-Agent regex
  device ||= Regexp.new(@regex_ua_catchall).match(user_agent) != nil

  if device
    device = device.to_s

    env[X_HEADER] = device
    redirect = check_for_redirect(device)

    if redirect
      path = Rack::Utils.unescape(env['PATH_INFO'])
      return [301, {'Location' => redirect}, []] if redirect && path !~ /^#{redirect}/
    end
  end

  @app.call(env)
end

#check_for_redirect(device) ⇒ Object

Checks to see if any redirect options were passed in and returns the appropriate redirect or nil (if no redirect requested)



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# File 'lib/rack/mobile-detect.rb', line 169

def check_for_redirect(device)
  # Find the device-specific redirect in the map, if exists
  return @redirect_map[device] if @redirect_map && @redirect_map.has_key?(device)
  # Return global redirect, or nil
  return @redirect_to
end