Rails - Sep 2005 - US Date Handling in Rails

My application is built on Rails and MySQL. It will only be accepting US
formatted dates as input, however both Rails and MySQL are oriented around
ISO the format. I know I can convert a good portion of the entries using
ParseDate::parsedate but it does not appear this is how the conversion is
taking place when data is being transferred from the params hash into model
members.

Say I have a field ''sold_on'' of type DATE in the database.
Would the
following model code be along the right lines?

require ''parsedate''

# ...

# override assignment ... or has the type conversion already happened
# by this point?

def sold_on=(value)
  self[:sold_on] = ParseDate::parsedate(value, true)
end

def sold_on
  self[:sold_on].strftime(''%m-%d-%Y'')
end

# ...

If this is a good approach, is there a way to extract it from the individual
models so I don''t repeat myself :)?

Thanks

On Wednesday 07 September 2005 00:49, Steve Ross wrote:
> My application is built on Rails and MySQL. It will only be accepting
> US formatted dates as input, however both Rails and MySQL are
> oriented around ISO the format. I know I can convert a good portion
> of the entries using ParseDate::parsedate but it does not appear this
> is how the conversion is taking place when data is being transferred
> from the params hash into model members.
I''ve had to deal with this recently, too. Although I want to be able to
handle dates of different formats. The module below is a mixin for 
ActiveRecord. To activate it, in environment.rb, say, insert

ActiveRecord::Base.class_eval do
  include BoilerPlate::Model::I18n
end

Adapt it to your needs and taste.

HTH,
Michael


require ''active_record''
require ''date''


module BoilerPlate # :nodoc:
  module Model # :nodoc:

    # I18n support for ActiveRecord.
    # Currently, all that it does is define a class variable
    #
    #   ActiveRecord::Base.date_format
    #
    # and redefines +write_attribute+ to convert string values to dates
    # according to this format.
    module I18n

      def self.included(base)
        base.class_eval do
          unless method_defined?(:write_attribute_with_date_cast)
            
alias_method :write_attribute_without_date_cast, :write_attribute

            def write_attribute_with_date_cast(attr, value)
              if column_for_attribute(attr).type == :date
                value = cast_to_date(value)
              end
              write_attribute_without_date_cast(attr, value)
            end

            
alias_method :write_attribute, :write_attribute_with_date_cast

            cattr_accessor :date_format
            ActiveRecord::Base.date_format = ''%Y-%m-%d''
          end
        end
      end

      protected

      def cast_to_date(value)
        case value
        when String
          Date.strptime(value, ActiveRecord::Base.date_format) rescue 
nil ### FIXME rescue better
        when Date, Time
          value
        else
          raise ArgumentError, "Argument to cast_to_date must be a 
String, Date, or Time; was: #{value.inspect}"
        end
      end

    end
  end
end


-- 
Michael Schuerig                 Nothing is as brilliantly adaptive
mailto:michael-q5aiKMLteq4b1SvskN2V4Q@public.gmane.org       as selective
stupidity.
http://www.schuerig.de/michael/    --A.O. Rorty, The Deceptive Self