String Mapper

String Mapper is an extension of the String class to perform conversions based on dynamic mappings.

Requirements

String Mapper uses ActiveSupport's cattr_accessor.

Installation

$ script/plugin install git://github.com/nando/string-mapper.git

The plugin just add its lib path to LOAD_PATH in order to be explicitly required where needed (for example in test environment).

Howto

First of all require the lib:

require 'string-mapper'

Class function add_mapper allows the definition of a new target for conversions. For example, the call:

String.add_mapper :model

adds an instance method to_model to convert any String to something called "model". It also adds a class hash called model_mappings which can be used to define mappings:

String.model_mappings[/usuari[oa]$/i] = User
'Usuario'.to_model # => User class  

Optionally we can define the mappings adding the mapper:

String.add_mapper :model, {
  /usuari[oa]$/i  => User,
  /cat[áa]logo$/i => Catalog }
'Usuario'.to_model # => User class  
'Person'.to_model  # => nil

Also a block can be given to add_mapper to manage the default value when no mapping matches the string:

String.add_mapper(:number) { |string| string.to_i }
String.number_mappings = {
  /an?$/i => 1,
  /two$/i => 2 }
'an'.to_number   # => 1  
'two'.to_number  # => 2  
'1000'.to_model  # => 1000

Other use examples can be found in spec/string-mapper_spec.rb.

License

Copyright 2008, Fernando García Samblas <fernando.garcia at the-cocktail.com>

This software is released under the GPL License (see license agreement in COPYING).