Merge pull request #272 from wvengen/feature-unit_conversion

use ruby-units for unit parsing

Gemfile

@@ -39,6 +39,7 @@ gem "rails-settings-cached", "0.3.1"
 gem 'resque'
 gem 'whenever', require: false # For defining cronjobs, see config/schedule.rb
 gem 'protected_attributes'
+gem 'ruby-units'
 
 # we use the git version of acts_as_versioned, and need to include it in this Gemfile
 gem 'acts_as_versioned', git: 'git://github.com/technoweenie/acts_as_versioned.git'

Gemfile.lock

@@ -281,6 +281,7 @@ GEM
  rspec-rerun (0.1.3)
  rspec (>= 2.11.0)
  ruby-prof (0.14.2)
+ ruby-units (1.4.4)
  rubyzip (1.1.0)
  sass (3.2.14)
  sass-rails (4.0.1)
@@ -421,6 +422,7 @@ DEPENDENCIES
  rspec-rails
  rspec-rerun
  ruby-prof
+ ruby-units
  sass-rails (~> 4.0.0)
  select2-rails
  selenium-webdriver

app/models/article.rb

@@ -117,6 +117,7 @@ def shared_article
  # returns nil if units are eqal
  def convert_units
  if unit != shared_article.unit
+ # legacy, used by foodcoops in Germany
  if shared_article.unit == "KI" and unit == "ST" # 'KI' means a box, with a different amount of items in it
  # try to match the size out of its name, e.g. "banana 10-12 St" => 10
  new_unit_quantity = /[0-9\-\s]+(St)/.match(shared_article.name).to_s.to_i
@@ -126,13 +127,13 @@ def convert_units
  else
  false
  end
- else # get factors for fc and supplier
- fc_unit_factor = FoodsoftConfig[:units][self.unit]
- supplier_unit_factor = FoodsoftConfig[:units][self.shared_article.unit]
- if fc_unit_factor and supplier_unit_factor
- convertion_factor = fc_unit_factor / supplier_unit_factor
- new_price = BigDecimal((convertion_factor * shared_article.price).to_s).round(2)
- new_unit_quantity = ( 1 / convertion_factor) * shared_article.unit_quantity
+ else # use ruby-units to convert
+ fc_unit = (::Unit.new(unit) rescue nil)
+ supplier_unit = (::Unit.new(shared_article.unit) rescue nil)
+ if fc_unit and supplier_unit and fc_unit =~ supplier_unit
+ conversion_factor = (fc_unit.convert_to(supplier_unit.units) / supplier_unit).scalar
+ new_price = shared_article.price * conversion_factor
+ new_unit_quantity = shared_article.unit_quantity / conversion_factor
  [new_price, new_unit_quantity]
  else
  false

config/app_config.yml.SAMPLE

@@ -91,22 +91,6 @@ default: &defaults
  encoding: utf8
  socket: /opt/lampp/var/mysql/mysql.sock
 
- # auto-units-conversion
- # this is used for automatic article-synchronization to handle different units
- # e.g. when foodcoop-unit should be 500g and supplier-unit is 1kg
- units:
- KG: 1
- 1kg: 1
- 500g: 0.5
- 400g: 0.4
- 300g: 0.3
- 250g: 0.25
- 200g: 0.2
- 150g: 0.15
- 125g: 0.125
- 100g: 0.1
- 50g: 0.05
-
 development:
  <<: *defaults
 

config/initializers/ruby_units.rb

@@ -0,0 +1,37 @@
+# add some more units
+
+if defined? RubyUnits
+ RubyUnits::Unit.redefine!('liter') do |unit|
+ unit.aliases += %w{ltr}
+ end
+
+ RubyUnits::Unit.redefine!('kilogram') do |unit|
+ unit.aliases += %w{KG}
+ end
+
+ RubyUnits::Unit.redefine!('gram') do |unit|
+ unit.aliases += %w{gr}
+ end
+
+ RubyUnits::Unit.define('piece') do |unit|
+ unit.definition = RubyUnits::Unit.new('1 each')
+ unit.aliases = %w{pc pcs piece pieces} # locale: en
+ unit.aliases += %w{st stuk stuks} # locale: nl
+ unit.kind = :counting
+ end
+
+ # we use pc for piece, not parsec
+ RubyUnits::Unit.redefine!('parsec') do |unit|
+ unit.aliases = unit.aliases.reject {|u| u=='pc'}
+ unit.display_name = 'parsec'
+ end
+
+ # workaround for ruby-units' require mathn warning: "zero and implicit precision is deprecated."
+ # default precision of 8 which same as all database definitions in db/migrate/20131213002332_*.rb
+ class Rational
+ alias orig_to_d to_d
+ def to_d(precision=8)
+ orig_to_d(precision)
+ end
+ end
+end