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Some [hopefully] useful extensions to Ruby's String class. Stringex is made up of three libraries: ActsAsUrl [permalink solution with better character translation], Unidecoder [Unicode to ASCII transliteration], and StringExtensions [miscellaneous helper methods for the String class].


= 0.7.0
= 2.3.7
= 4.2.9
= 1.3.10
= 3.0.9
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Some [hopefully] useful extensions to Ruby's String class. It is made up of three libraries: ActsAsUrl, Unidecoder, and StringExtensions.

NOTE: Stringex 2.0 [and beyond] drops support for Rails 2. If you need support for that version, use 1.5.1 instead.


NOTE: You can now require 'stringex_lite' instead of 'stringex' and skip loading ActsAsUrl functionality if you don't need it.

This library is designed to create URI-friendly representations of an attribute, for use in generating urls from your attributes. Basic usage is just calling the method:

# Inside your model
acts_as_url :title

which will populate the url attribute on the object with the converted contents of the title attribute. acts_as_url takes the following options:

:url_attribute The name of the attribute to use for storing the generated url string. Default is :url
:scope The name of model attribute to scope unique urls to. There is no default here.
:only_when_blank If set to true, the url generation will only happen when :url_attribute is blank. Default is false (meaning url generation will happen always).
:sync_url If set to true, the url field will be updated when changes are made to the attribute it is based on. Default is false.
:allow_slash If set to true, the url field will not convert slashes. Default is false.
:allow_duplicates If set to true, unique urls will not be enforced. Default is false. NOTE: This is strongly not recommended if you are routing solely on the generated slug as you will no longer be guaranteed to lookup the expected record based on a duplicate slug.
:limit If set, will limit length of url generated. Default is nil.
:truncate_words Used with :limit. If set to false, the url will be truncated to the last whole word before the limit was reached. Default is true.
:blacklist List of urls that should not be allowed. Default is %w{new} [which avoids confusion on urls like /documents/new].
:blacklist_policy Proc or lambda defining new naming behavior when blacklisted urls are encountered. Default converts /documents/new to /documents/new-document.

In order to use the generated url attribute, you will probably want to override to_param like so, in your Model:

# Inside your model
def to_param
  url # or whatever you set :url_attribute to

Routing called via named routes like foo_path(@foo) will automatically use the url. In your controllers you will need to call Foo.find_by_url(params[:id]) instead of the regular find. Don't look for params[:url] unless you set it explicitly in the routing, to_param will generate params[:id].

Note that if you add acts_as_url to an existing model, the url database column will initially be blank. To set this column for your existing instances, you can use the initialize_urls method. So if your class is Post, just say Post.initialize_urls.

Unlike other permalink solutions, ActsAsUrl doesn't rely on Iconv (which is inconsistent across platforms and doesn't provide great transliteration as is) but instead uses a transliteration scheme (see the code for Unidecoder) which produces much better results for Unicode characters. It also mixes in some custom helpers to translate common characters into a more URI-friendly format rather than just dump them completely. Examples:

# A simple prelude
"simple English".to_url => "simple-english"
"it's nothing at all".to_url => "its-nothing-at-all"
"rock & roll".to_url => "rock-and-roll"

# Let's show off
"$12 worth of Ruby power".to_url => "12-dollars-worth-of-ruby-power"
"10% off if you act now".to_url => "10-percent-off-if-you-act-now"

# You dont EVEN wanna rely on Iconv for this next part
"kick it en Français".to_url => "kick-it-en-francais"
"rock it Español style".to_url => "rock-it-espanol-style"
"tell your readers 你好".to_url => "tell-your-readers-ni-hao"

Compare those results with the ones produced on my Intel Mac by a leading permalink plugin:

"simple English" # => "simple-english"
"it's nothing at all" # => "it-s-nothing-at-all"
"rock & roll" # => "rock-roll"

"$12 worth of Ruby power" # => "12-worth-of-ruby-power"
"10% off if you act now" # => "10-off-if-you-act-now"

"kick it en Français" # => "kick-it-en-francais"
"rock it Español style" # => "rock-it-espan-ol-style"
"tell your readers 你好" # => "tell-your-readers"

Not so great, actually.

Note: No offense is intended to the author(s) of whatever plugins might produce such results. It's not your faults Iconv sucks.


This library converts Unicode [and accented ASCII] characters to their plain-text ASCII equivalents. This is a port of Perl's Unidecode and provides eminently superior and more reliable results than Iconv. (Seriously, Iconv... A plague on both your houses! [sic])

You may require only the unidecoder (and its dependent localization) via

require "stringex/unidecoder"

You probably won't ever need to run Unidecoder by itself. Thus, you probably would want to add String#to_ascii which wraps all of Unidecoder's functionality, by requiring:

require "stringex/core_ext"

For anyone interested, details of the implementation can be read about in the original implementation of Text::Unidecode. Extensive examples can be found in the tests.


A small collection of extensions on Ruby's String class. Please see the documentation for StringExtensions module for more information. There's not much to explain about them really.


With Stringex version 2.0 and higher, you can localize the different conversions in Stringex. Read more here. If you add a new language, please submit a pull request so we can make it available to other users also.

Ruby on Rails Usage

When using Stringex with Ruby on Rails, you automatically get built-in translations for miscellaneous characters, HTML entities, and vulgar fractions. You can see Stringex's standard translations here.

Currently, built-in translations are available for the following languages:

  • English (en)
  • Danish (da)
  • Swedish (sv)
  • Dutch (nl)
  • German (de)
  • Polish (pl)
  • Portuguese Brazilian (pt-BR)
  • Russian (ru)

You can easily add your own or customize the built-in translations - read here. If you add a new language, please submit a pull request so we can make it available to other users also.

If you don't want to use the Stringex built-in translations, you can force Stringex to use English (or another language), regardless what is in your I18n.locale. In an initializer, e.g. config/initializers/stringex.rb:

Stringex::Localization.locale = :en

CanCan Usage Note

You'll need to add a :find_by => :url to your load_and_authorize_resource. Here's an example:

load_and_authorize_resource :class => "Whatever", :message => "Not authorized", :find_by => :url

Semantic Versioning

This project conforms to semver. As a result of this policy, you can (and should) specify a dependency on this gem using the Pessimistic Version Constraint with two digits of precision. For example:

spec.add_dependency 'stringex', '~> 1.0'

This means your project is compatible with licensee 1.0 up until 2.0. You can also set a higher minimum version:

spec.add_dependency 'stringex', '~> 1.1'

Thanks & Acknowledgements

If it's not obvious, some of the code for ActsAsUrl is based on Rick Olsen's permalink_fu plugin. Unidecoder is a Ruby port of Sean Burke's Text::Unidecode module for Perl. And, finally, the bulk of strip_html_tags in StringExtensions was stolen from Tobias Lütke's Regex in Typo.

GIANT thanks to the many contributors who have helped make Stringex better and better: http://github.com/rsl/stringex/contributors

Copyright (c) 2008-2018 Lucky Sneaks, released under the MIT license