I18n date/number parsing/localization
I18nAlchemy aims to handle date, time and number parsing, based on current I18n locale format. The main idea is to have ORMs, such as ActiveRecord for now, to automatically accept dates/numbers given in the current locale format, and return these values localized as well.
Almost all projects I've been working so far required some sort of input using dates and numbers, and it has always been a pain due to lack of this support in ActiveRecord itself. As I do most of my projects using different date/number formats than the English defaults (I live in Brazil), we've been adopting different ways to handle that in each application.
I've already used the delocalize gem in some of these projects, and validates_timeliness parser in others, and both work pretty well actually. But I think it might work a bit different than delocalize, and mainly, I wanted to learn more about I18n and ActiveRecord internals.
I18nAlchemy is pretty straigthforward to use, you just need to include it in your ActiveRecord model. Lets say we are working with a Product model:
class Product < ActiveRecord::Base include I18n::Alchemy end
By mixing the module into your model, you get the localized method:
@product = Product.first @localized = @product.localized
Here are some examples on how to use it with numeric values:
@localized.price = "1.99" @product.price # => 1.99 @localized.price # => "1.99" I18n.with_locale :pt do @localized.price = "1,88" @product.price # => 1.88 @localized.price # => "1,88" end
Please notice that the localized proxy also formats your numeric values based on the current precision in your I18n locale file:
@product.price = 1.3 @localized.price # => "1.30", considering a precision of 2
And with thousand separators as well:
@product.price = 1840.32 @localized.price # => "1,840.32", considering separator = "," and delimiter = "."
Some examples with date / time objects:
@localized.released_at = "12/31/2011" @product.released_at # => Date.new(2011, 12, 31) @localized.released_at # => "12/31/2011" I18n.with_locale :pt do @localized.released_at = "31/12/2011" @product.released_at # => Date.new(2011, 12, 31) @localized.released_at # => "31/12/2011" end
The localized method quacks like ActiveRecord: you can give a hash of attributes and extra options if you want, and it will delegate everything to the object, parsing the attributes before:
# This will parse the attributes in the given hash. I18n.with_locale :pt do @localized = @product.localized(:price => "1,88") @product.price # => 1.88 @localized.price # => "1,88" end
Given a product model with a
total method, that is a simple calculation of
quantity * price, you can tell I18n::Alchemy to localize that method for you together with the attributes:
class Product < ActiveRecord::Base include I18n::Alchemy localize :total, :using => :number def total quantity * price end end @product = Product.first @product.price = 1.99 @product.quantity = 10 @product.total # => 19.90 @localized.total # => "19,90"
If the method has a writer method, in this case
total=, that'd get a parsed version for input values as well.
localize is possible to localize objects that aren't inheriting from
ActiveRecord::Base, as long that
your class have both reader and writer methods available:
class Product include I18n::Alchemy localize :released_at, :using => :date attr_accessor :released_at end
If you want to customize the way an attribute is parsed/localized, you can create a custom parser that looks like this:
module MyCustomDateParser include I18n::Alchemy::DateParser extend self def localize(value) I18n.localize value, :format => :custom end protected def i18n_format I18n.t(:custom, :scope => [:date, :formats]) end end
And then just configure the attribute you want to use with this new parser:
class Product < ActiveRecord::Base include I18n::Alchemy custom_parsers :released_month => MyCustomDateParser end
By doing this, I18n::Alchemy will be set up to use your custom parser for that particular attribute, which in this case will make use of the
:custom date format in your i18n locale.
If you are using
localize, you can mix the custom parsers with your existing configuration:
class Product < ActiveRecord::Base include I18n::Alchemy localize :total, :using => MyCustomNumberParser end
Right now the lib uses the same configuration for numeric, date and time values from Rails:
en: date: formats: default: "%m/%d/%Y" time: formats: default: "%m/%d/%Y %H:%M:%S" number: format: separator: '.' delimiter: ',' precision: 2
Please notice the default date and time format is considered for input values for now, and it will only accept valid values matching these formats. We plan to add specific formats and to parse a list of possible input formats for I18nAlchemy, to make it more flexible, please refer to TODO file for more info.
Carlos Antonio da Silva (http://github.com/carlosantoniodasilva)