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Date/time and number parsing for Rails.



Build Status

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

1.0 Beta

Check out the 1-0-beta branch for an unfinished/unreleased improved version of delocalize. The goal is to get rid of all the nasty hacks and have a library that doesn't break with every new release of Rails.

Also check out the ongoing discussion the wiki and feel free to put in your opinion there.


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 and Rails 4

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.

What does it do? And how do I use it?

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(',', '.'))

delocalize does this under the covers -- all you need is your regular translation data (as YAML or Ruby file) where you need Rails' standard translations:

      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" %>

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 in Ruby 1.9.3, Ruby 2.0 and Ruby 2.1 (head)
  • Tested with Rails 4 in Ruby 1.9.3, Ruby 2.0 and Ruby 2.1 (head)


Thanks to all the people who contributed and submitted issues.


  • Improve test coverage
  • Separate Ruby/Rails stuff to make it usable outside Rails
  • Decide on other ActionView hacks (e.g. text_field_tag)
  • Implement AM/PM support
  • Cleanup, cleanup, cleanup ...

Copyright (c) 2009-2014 Clemens Kofler Released under the MIT license

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