Rails - Nov 2007 - Working with one model from another

Hi all,

I have some code where I''d like to set up an instance of a non-database
model from another, ActiveRecord, model in order to use some custom
methods on a string, without mixing extra methods into the String class.
I understand this might be less-than-sensible as models should normally
stand on their own..?

My two models:


#######################
# models/qualified_name.rb #
#######################

# t.column :make,             :text
# t.column :model,            :text
# t.column :origin_country,   :text

class QualifiedName < ActiveRecord::Base

  # Work some magic -- let''s populate the instance using the raw name
string (e.g. "Honda Civic")
  def magically_understand(name_string)
    raw_name = RawName.new(name_string)

    if raw_name.is_one_word then
      self.make = raw_name.contents
    else
      if raw_name.is_two_words then
        self.make = raw_name.words.first
        self.model = raw_name.words.last
      end
    end
    if raw_name.make_could_be_japanese then
      self.origin_country = "Japan"
    end

  return true

  end

end


###################
# models/raw_name.rb #
###################

class RawName

  def initialize(contents)
    @contents = contents
    @words = @contents.split('' '')
  end

  def contents
    @contents
  end

  # Nice to be able to say raw_name.words.first
  def words
    @words
  end

  # Is the string just one word long? Return boolean.
  def is_one_word
    @words.length == 1
  end

  # Is the string two words long? Return boolean.
  def is_two_words
    @words.length == 2
  end

  # Work out whether the first word (the make) ends in -a, -i or -u
  def make_could_be_japanese
    if @words.first.last(1) =~ /[aiu$]$/i : return true
    else
      return false
    end
  end

end

###

and so I want to be able to do the following kind of thing:
>> name = QualifiedName.new
=> #<QualifiedName:0x353df60 @new_record=true,
@attributes={"origin_country"=>nil, "make"=>nil,
"model"=>nil}>
>> name.magically_understand("Honda Civic")
=> nil
>> name
=> #<QualifiedName:0x353df60 @new_record=true,
@attributes={"origin_country"=>"Japan",
"make"=>"Honda",
"model"=>"Civic"}>

All this model code is of course very verbose, but it''s obviously just
an example. I know there are simpler ways to get this particular result,
but I want to be able to do more complex analyses of the ''raw
name'' and
populate the qualified name accordingly.

Is there a more maintanable structure I could be looking at? Should I
ditch the RawName model altogether and do everything within
QualifiedName - and if so how should I declare the helper methods like
make_could_be_japanese?

Thanks for any thoughts or inspiration!

Toby
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