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delocalize provides localized date/time and number parsing functionality for Rails.


You can use delocalize as a gem (preferred). Using delocalize as a Rails plugin has been discontinued and is no supported. If you want/need to use delocalize as a gem (I really don't see a reason why you'd want to), consider using the 0-2-stable branch.

Rails 3

To use delocalize, put the following gem requirement in your Gemfile:

gem "delocalize"

Rails 2

Note: Support for Rails 2 has been discontinued. This version is only considered stable for Rails 3. If you need Rails 2 support, please use the 0.2.x versions or the 0-2-stable branch respectively.

To use delocalize, put the following gem requirement in your environment.rb:

config.gem "delocalize", :source => ''

In Rails 2.3, alternatively, you can use it with Bundler. See for instructions.

Use case and usage

Delocalize, just as the name suggest, does pretty much the opposite of localize.

In the grey past, if you want your users to be able to input localized data, such as dates and numbers, you had to manually override attribute accessors:

def price=(price)
  write_attribute(:price, price.gsub(',', '.'))

You also had to take care of proper formatting in forms on the frontend so people would see localized values in their forms.

Delocalize does most of this under the covers. All you need is a simple declaration and your regular translation data (as YAML or Ruby file) where you need Rails' standard translations.

Usage in a model

class Product < ActiveRecord::Base
  delocalize :price => :number, :released_on => :date, :published_at => :time

Usage outside of Rails/ActiveRecord

Delocalize should – in theory – work independently of Rails and ActiveRecord.

To use Delocalize for your own non-ActiveRecord models, just include the Delocalizable module:

class Product
  include Delocalize::Delocalizable

Caveat: Delocalize currently expects that it can call a method named write_attribute – so make sure it's there! This might change as soon as I figure out a better way to do this.

As for the view part, you're on your own – Delocalize only supports ActionView right now.

If you run into any issues with using Delocalize outside Rails, please file an issue. I'm happy to take a look at it.

Sample translation file

      separator: ','
      delimiter: '.'
      formats: [:default, :long, :short] # <- this and ...

      default: "%d.%m.%Y"
      short: "%e. %b"
      long: "%e. %B %Y"
      only_day: "%e"

    day_names: [Sonntag, Montag, Dienstag, Mittwoch, Donnerstag, Freitag, Samstag]
    abbr_day_names: [So, Mo, Di, Mi, Do, Fr, Sa]
    month_names: [~, Januar, Februar, März, April, Mai, Juni, Juli, August, September, Oktober, November, Dezember]
    abbr_month_names: [~, Jan, Feb, Mär, Apr, Mai, Jun, Jul, Aug, Sep, Okt, Nov, Dez]
    order: [ :day, :month, :year ]

      formats: [:long, :medium, :short, :default, :time] # <- ... this are the only non-standard keys
      default: "%A, %e. %B %Y, %H:%M Uhr"
      short: "%e. %B, %H:%M Uhr"
      long: "%A, %e. %B %Y, %H:%M Uhr"
      time: "%H:%M"

    am: "vormittags"
    pm: "nachmittags"

For dates and times, you have to define input formats which are taken from the actual formats. The important thing here is to define input formats sorted by descending complexity; in other words: the format which contains the most (preferably non-numeric) information should be first in the list because it can produce the most reliable match. Exception: If you think there most complex format is not the one that most users will input, you can put the most-used in front so you save unnecessary iterations.

Careful with formats containing only numbers: It's very hard to produce reliable matches if you provide multiple strictly numeric formats!

delocalize then overrides to_input_field_tag in ActionView's InstanceTag so you can use localized text fields:

<% form_for @product do |f| %>
  <%= f.text_field :name %>
  <%= f.text_field :released_on %>
  <%= f.text_field :price %>
<% end %>

In this example, a user can enter the release date and the price just like he's used to in his language, for example:

Name: "Couch"
Released on: "12. Oktober 2009"
Price: "2.999,90"

When saved, ActiveRecord automatically converts these to a regular Ruby date and number.

Edit forms then also show localized dates/numbers. By default, dates and times are localized using the format named :default in your locale file. So with the above locale file, dates would use %d.%m.%Y and times would use %A, %e. %B %Y, %H:%M Uhr. Numbers are also formatted using your locale's thousands delimiter and decimal separator.

You can also customize the output using some options:

The price should always show two decimal digits and we don't need the delimiter: <%= f.text_field :price, :precision => 2, :delimiter => '' %>

The released_on date should be shown in the :full format: <%= f.text_field :released_on, :format => :full %>

Since I18n.localize supports localizing strftime strings, we can also do this: <%= f.text_field :released_on, :format => "%B %Y" %>


Update from 0.x.x to 1.x.x

Delocalize underwent a major API change – hence the incremented major version number. The whole code base is much cleaner now because it lost much of the magic that shouldn't have been there in the first place.

If you haven't been hacking around in Delocalize's hacks (I hope you haven't ;-)), all you should have to do is declare all the fields you want Delocalize to pick up in their respective models. See the usage example for details.

Ruby 1.9 + Psych YAML Parser

You will need to adjust the localization formatting when using the new YAML parser Psych. Below is an example error message you may receive in your logs as well as an example of acceptable formatting and helpful links for reference:

Error message from logs:

Psych::SyntaxError (couldn't parse YAML at line x column y):


The solution can be found here:

Psych Preferred Formatting:

      separator: '.'
      delimiter: ','
      precision: 2
        - :default
        - :long
        - :short
      default: "%m/%d/%Y"
      short: "%b %e"
      long: "%B %e, %Y"
      only_day: "%e"
      - Sunday
      - Monday
      - Tuesday
      - Wednesday
      - Thursday
      - Friday
      - Saturday
      - Sun
      - Mon
      - Tue
      - Wed
      - Thur
      - Fri
      - Sat
      - ~
      - January
      - February
      - March
      - April
      - May
      - June
      - July
      - August
      - September
      - October
      - November
      - December
      - ~
      - Jan
      - Feb
      - Mar
      - Apr
      - May
      - Jun
      - Jul
      - Aug
      - Sep
      - Oct
      - Nov
      - Dec
      - :month
      - :day
      - :year
        - :default
        - :long
        - :short
        - :time
      default: "%m/%d/%Y %I:%M%p"
      short: "%B %e %I:%M %p"
      long: "%A, %B %e, %Y %I:%M%p"
      time: "%l:%M%p"
    am: "am"
    pm: "pm"


  • Tested with Rails 2.3.5 in Ruby 1.8.7, Ruby 1.9.1 and Ruby 1.9.2 (head)
  • Tested with Rails 3 Beta 3 in Ruby 1.9.2 (head)


People who have contributed to delocalize (in no particular order):


  • Improve test coverage
  • Implement AM/PM support

Copyright (c) 2009-2012 Clemens Kofler and contributors. Released under the MIT license

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