WIP: Add dynamic helper instance methods

lib/trasto/instance_methods.rb

@@ -1,20 +1,85 @@
 module Trasto
   module InstanceMethods
+    def self.included(base)
+      prepend HstoreUpdatePatch if ActiveRecord::VERSION::STRING < "4.2.0"
+      super
+    end
+
+    def method_missing(method, *args, &block)
+      # Return super only if above can respond without us.
+      # If we call super and above cannot respond without us,
+      # infinite recursion occurs.
+      return super if respond_to?(method) && !respond_to_missing?(method)
+
+      if match = match_translate_method(method)
+        # We define accessors after getting the value in the hopes of
+        # capturing a new locale that would be useful.
+        return access_translated_value(*match, args).tap do
+          define_translation_accessors!
+        end
+      end
+
+      super
+    end
+
+    def respond_to_missing?(method, include_privates = false)
+      !!match_translate_method(method)
+    end
+
+    def define_translation_accessors!
+      self.class.translatable_columns.each do |column|
+        return unless column_value = send("#{column}_i18n")
+
+        column_value.keys.each do |locale|
+          define_singleton_method "#{column}_#{locale}" do
+            read_translated_value(column, locale)
+          end
+
+          define_singleton_method "#{column}_#{locale}=" do |value|
+            write_translated_value(column, locale, value)
+          end
+        end
+      end
+    end
+
     private
 
+    def access_translated_value(column, locale, write_mode, args = [])
+      if write_mode
+        write_translated_value(column, locale, args[0])
+      else
+        read_translated_value(column, locale)
+      end
+    end
+
+    # Finds a suitable translation for column
     def read_localized_value(column)
       return nil unless (column_value = send("#{column}_i18n"))
+      column_value = column_value.with_indifferent_access # Rails < 4.1
 
       locales_for_reading_column(column).each do |locale|
         value = column_value[locale]
         return value if value.present?
       end
+
       nil
     end
 
+    # Reads column value in specified locale
+    def read_translated_value(column, locale)
+      return unless column_value = send("#{column}_i18n")
+      column_value = column_value.with_indifferent_access
+      column_value[locale]
+    end
+
     def write_localized_value(column, value)
+      write_translated_value(column, I18n.locale, value)
+    end
+
+    def write_translated_value(column, locale, value)
       translations = send("#{column}_i18n") || {}
-      send("#{column}_i18n=", translations.merge(I18n.locale => value).with_indifferent_access)
+      translations.merge!(locale => value).with_indifferent_access
+      send("#{column}_i18n=", translations)
     end
 
     def locales_for_reading_column(column)
@@ -26,5 +91,27 @@ def locales_for_reading_column(column)
         end
       end
     end
+
+    # Returns an array with column, name and maybe equal if match, else
+    # returns nil.
+    #
+    # [column, locale, "=" or nil]
+    def match_translate_method(method)
+      ary = method.to_s.scan(/^(.*)_([a-z]{2})(=)?$/).flatten
+      return nil if ary.empty?
+
+      ary if self.class.translates?(ary[0])
+    end
+
+    # Patches an ActiveRecord bug that wouldn't update the hstore when
+    # changed. Affects 4.0, 4.1.
+    #
+    # See https://github.com/rails/rails/issues/6127
+    module HstoreUpdatePatch
+      def write_translated_value(column, locale, value)
+        send("#{column}_i18n_will_change!")
+        super
+      end
+    end
   end
 end

spec/spec_helper.rb

@@ -5,6 +5,14 @@
     Object.send(:remove_const, 'SubPost')
     load 'app/post.rb'
   end
+
+  # If you really need a clean run (for eg. Travis)
+  # config.after :suite do
+  #   ActiveRecord::Base.connection.execute <<-eosql
+  #     DROP TABLE posts;
+  #     DROP EXTENSION IF EXISTS hstore CASCADE;
+  #   eosql
+  # end
 end
 
 # Test against real ActiveRecord models.
@@ -23,11 +31,12 @@
 
 silence_stream(STDOUT) do
   ActiveRecord::Schema.define(version: 0) do
-    execute 'CREATE EXTENSION IF NOT EXISTS hstore'
+    enable_extension "hstore"
 
     create_table :posts, force: true do |t|
       t.hstore :title_i18n
       t.hstore :body_i18n
+      t.string :constant
     end
   end
 end

spec/trasto_spec.rb

@@ -23,6 +23,13 @@
     expect(Post.new).to respond_to :title
     expect(Post.new).not_to respond_to :body
   end
+
+  it "should leave other columns intact" do
+    Post.translates :title
+    post = Post.new(constant: "tau")
+
+    expect(post.constant).to eq "tau"
+  end
 end
 
 describe ActiveRecord::Base, '.translates?' do
@@ -89,6 +96,15 @@
     post.title_i18n = nil
     expect(post.title).to be_nil
   end
+
+  it "should generate helper methods" do
+    expect(post.title_en).to eq "Hello"
+  end
+
+  it "should be able to persist" do
+    post.save; post.reload
+    expect(post.title_i18n['en']).to eq "Hello"
+  end
 end
 
 describe Post, '#title=' do
@@ -102,6 +118,86 @@
   it 'should assign in the current locale' do
     post.title = 'Hallo'
     expect(post.title).to eq('Hallo')
-    expect(post.title_i18n['de']).to eq('Hallo')
+    expect(post.title_i18n.with_indifferent_access['de']).to eq('Hallo')
+  end
+end
+
+describe Post, "dynamic accessors" do
+  before do
+    Post.translates :title
+    I18n.locale = :en
+  end
+
+  let(:post) do
+    Post.new(title_i18n: {
+      en: "Free breakfast",
+      fr: "Déjeuner gratuit",
+    })
+  end
+
+  it "should respond_to title_en" do
+    expect(post).to respond_to(:title_en)
+  end
+
+  describe "#title_en" do
+    it "should return the localized value" do
+      expect(post.title_en).to eq "Free breakfast"
+      expect(post.title_fr).to eq "Déjeuner gratuit"
+      expect(post.title_es).to be nil
+    end
+
+    it "should define readers when used" do
+      post.title_en
+      expect(post.methods.include?(:title_en)).to be true
+      expect(post.methods.include?(:title_fr)).to be true
+      expect(post.title_en).to eq "Free breakfast"
+      expect(post.title_fr).to eq "Déjeuner gratuit"
+    end
+
+    it "should not define accessors until used" do
+      expect(post.methods.include?(:title_en)).to be false
+      expect(post.methods.include?(:title_fr)).to be false
+    end
+
+    it "should work with an empty field" do
+      post = Post.new
+      expect(post.title_en).to be nil
+    end
+  end
+
+  describe "#title_es=" do
+    it "should write the localized value" do
+      post.title_es = "Desayuno gratis"
+      expect(post.title_i18n["es"]).to eq "Desayuno gratis"
+    end
+
+    it "should define writers when used" do
+      post.title_es = "Desayuno gratis"
+      expect(post.methods.include?(:title_en=)).to be true
+      expect(post.methods.include?(:title_es=)).to be true
+      expect(post.title_es).to eq "Desayuno gratis"
+    end
+
+    it "should not define accessors until used" do
+      expect(post.methods.include?(:title_en=)).to be false
+      expect(post.methods.include?(:title_es=)).to be false
+    end
+
+    it "should work in mass attribute assignment" do
+      newpost = Post.new(title_en: "Great job", title_fr: "Beau travail")
+      expect(newpost.title_en).to eq "Great job"
+      expect(newpost.title_fr).to eq "Beau travail"
+    end
+  end
+
+  describe "#title_fr=" do
+    it "should update existing hstore in AR 4.1" do
+      post.save; post.reload
+
+      post.title_fr = "Nouveau"
+      post.save; post.reload
+
+      expect(post.title_fr).to eq "Nouveau"
+    end
   end
 end