Merge pull request #457 from michaelherold/copying-in-trash

Allow Trash to copy properties from other properties

5 files changed, 133 insertions, 36 deletions

diff --git a/.rubocop_todo.yml b/.rubocop_todo.yml
index 5900e3f..e4e05c7 100644
--- a/.rubocop_todo.yml
+++ b/.rubocop_todo.yml
@@ -1,16 +1,16 @@
 # This configuration was generated by
 # `rubocop --auto-gen-config`
-# on 2018-02-07 19:58:08 -0600 using RuboCop version 0.52.1.
+# on 2018-08-11 15:53:09 -0500 using RuboCop version 0.52.1.
 # The point is for the user to remove these configuration records
 # one by one as the offenses are removed from the code base.
 # Note that changes in the inspected code, or installation of new
 # versions of RuboCop, may require this file to be generated again.
 
-# Offense count: 9
+# Offense count: 8
 Metrics/AbcSize:
-  Max: 26
+  Max: 24
 
-# Offense count: 57
+# Offense count: 58
 # Configuration parameters: CountComments, ExcludedMethods.
 Metrics/BlockLength:
   Max: 620
@@ -42,14 +42,13 @@ Metrics/PerceivedComplexity:
 Style/Documentation:
   Enabled: false
 
-# Offense count: 2
+# Offense count: 1
 # Cop supports --auto-correct.
 Style/IfUnlessModifier:
   Exclude:
-    - 'lib/hashie/extensions/dash/property_translation.rb'
     - 'lib/hashie/extensions/strict_key_access.rb'
 
-# Offense count: 256
+# Offense count: 261
 # Configuration parameters: AllowHeredoc, AllowURI, URISchemes, IgnoreCopDirectives, IgnoredPatterns.
 # URISchemes: http, https
 Metrics/LineLength:
diff --git a/CHANGELOG.md b/CHANGELOG.md
index f04a249..365ecfc 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -32,6 +32,7 @@ scheme are considered to be bugs.
 * [#436](https://github.com/intridea/hashie/pull/436): Ensure that `Hashie::Extensions::IndifferentAccess` injects itself after a non-destructive merge - [@michaelherold](https://github.com/michaelherold).
 * [#437](https://github.com/intridea/hashie/pull/437): Allow codependent properties to be set on Dash - [@michaelherold](https://github.com/michaelherold).
 * [#438](https://github.com/intridea/hashie/pull/438): Fix: `NameError (uninitialized constant Hashie::Extensions::Parsers::YamlErbParser::Pathname)` in `Hashie::Mash.load` - [@onk](https://github.com/onk).
+* [#457](https://github.com/intridea/hashie/pull/457): Fix `Trash` to allow it to copy properties from other properties - [@michaelherold](https://github.com/michaelherold).
 * Your contribution here.
 
 ### Security
diff --git a/lib/hashie/dash.rb b/lib/hashie/dash.rb
index ee27b11..4e366ed 100644
--- a/lib/hashie/dash.rb
+++ b/lib/hashie/dash.rb
@@ -42,11 +42,8 @@ module Hashie
         defaults.delete property_name
       end
 
-      unless instance_methods.map(&:to_s).include?("#{property_name}=")
-        define_method(property_name) { |&block| self.[](property_name, &block) }
-        property_assignment = "#{property_name}=".to_sym
-        define_method(property_assignment) { |value| self.[]=(property_name, value) }
-      end
+      define_getter_for(property_name)
+      define_setter_for(property_name)
 
       @subclasses.each { |klass| klass.property(property_name, options) } if defined? @subclasses
 
@@ -61,9 +58,11 @@ module Hashie
 
     class << self
       attr_reader :properties, :defaults
+      attr_reader :getters
       attr_reader :required_properties
     end
     instance_variable_set('@properties', Set.new)
+    instance_variable_set('@getters', Set.new)
     instance_variable_set('@defaults', {})
     instance_variable_set('@required_properties', {})
 
@@ -71,6 +70,7 @@ module Hashie
       super
       (@subclasses ||= Set.new) << klass
       klass.instance_variable_set('@properties', properties.dup)
+      klass.instance_variable_set('@getters', getters.dup)
       klass.instance_variable_set('@defaults', defaults.dup)
       klass.instance_variable_set('@required_properties', required_properties.dup)
     end
@@ -87,6 +87,18 @@ module Hashie
       required_properties.key? name
     end
 
+    private_class_method def self.define_getter_for(property_name)
+      return if getters.include?(property_name)
+      define_method(property_name) { |&block| self.[](property_name, &block) }
+      getters << property_name
+    end
+
+    private_class_method def self.define_setter_for(property_name)
+      setter = :"#{property_name}="
+      return if instance_methods.include?(setter)
+      define_method(setter) { |value| self.[]=(property_name, value) }
+    end
+
     # You may initialize a Dash with an attributes hash
     # just like you would many other kinds of data objects.
     def initialize(attributes = {}, &block)
diff --git a/lib/hashie/extensions/dash/property_translation.rb b/lib/hashie/extensions/dash/property_translation.rb
index 2d28080..85bfb89 100644
--- a/lib/hashie/extensions/dash/property_translation.rb
+++ b/lib/hashie/extensions/dash/property_translation.rb
@@ -40,7 +40,7 @@ module Hashie
       module PropertyTranslation
         def self.included(base)
           base.instance_variable_set(:@transforms, {})
-          base.instance_variable_set(:@translations_hash, {})
+          base.instance_variable_set(:@translations_hash, ::Hash.new { |hash, key| hash[key] = {} })
           base.extend(ClassMethods)
           base.send(:include, InstanceMethods)
         end
@@ -72,21 +72,16 @@ module Hashie
           def property(property_name, options = {})
             super
 
-            if options[:from]
-              if property_name == options[:from]
-                raise ArgumentError, "Property name (#{property_name}) and :from option must not be the same"
-              end
-
-              translations_hash[options[:from]] ||= {}
-              translations_hash[options[:from]][property_name] = options[:with] || options[:transform_with]
+            from = options[:from]
+            converter = options[:with]
+            transformer = options[:transform_with]
 
-              define_method "#{options[:from]}=" do |val|
-                self.class.translations_hash[options[:from]].each do |name, with|
-                  self[name] = with.respond_to?(:call) ? with.call(val) : val
-                end
-              end
-            elsif options[:transform_with].respond_to? :call
-              transforms[property_name] = options[:transform_with]
+            if from
+              fail_self_transformation_error!(property_name) if property_name == from
+              define_translation(from, property_name, converter || transformer)
+              define_writer_for_source_property(from)
+            elsif valid_transformer?(transformer)
+              transforms[property_name] = transformer
             end
           end
 
@@ -103,26 +98,49 @@ module Hashie
           end
 
           def translations
-            @translations ||= {}.tap do |h|
+            @translations ||= {}.tap do |translations|
               translations_hash.each do |(property_name, property_translations)|
-                h[property_name] = if property_translations.size > 1
-                                     property_translations.keys
-                                   else
-                                     property_translations.keys.first
-                                   end
+                translations[property_name] =
+                  if property_translations.size > 1
+                    property_translations.keys
+                  else
+                    property_translations.keys.first
+                  end
               end
             end
           end
 
           def inverse_translations
-            @inverse_translations ||= {}.tap do |h|
+            @inverse_translations ||= {}.tap do |translations|
               translations_hash.each do |(property_name, property_translations)|
-                property_translations.each_key do |k|
-                  h[k] = property_name
+                property_translations.each_key do |key|
+                  translations[key] = property_name
                 end
               end
             end
           end
+
+          private
+
+          def define_translation(from, property_name, translator)
+            translations_hash[from][property_name] = translator
+          end
+
+          def define_writer_for_source_property(property)
+            define_method "#{property}=" do |val|
+              __translations[property].each do |name, with|
+                self[name] = with.respond_to?(:call) ? with.call(val) : val
+              end
+            end
+          end
+
+          def fail_self_transformation_error!(property_name)
+            raise ArgumentError, "Property name (#{property_name}) and :from option must not be the same"
+          end
+
+          def valid_transformer?(transformer)
+            transformer.respond_to? :call
+          end
         end
 
         module InstanceMethods
@@ -132,6 +150,7 @@ module Hashie
           def []=(property, value)
             if self.class.translation_exists? property
               send("#{property}=", value)
+              super(property, value) if self.class.properties.include?(property)
             elsif self.class.transformation_exists? property
               super property, self.class.transformed_property(property, value)
             elsif property_exists? property
@@ -156,6 +175,12 @@ module Hashie
             fail_no_property_error!(property) unless self.class.property?(property)
             true
           end
+
+          private
+
+          def __translations
+            self.class.translations_hash
+          end
         end
       end
     end
diff --git a/spec/hashie/trash_spec.rb b/spec/hashie/trash_spec.rb
index 20b717c..043cbfd 100644
--- a/spec/hashie/trash_spec.rb
+++ b/spec/hashie/trash_spec.rb
@@ -265,4 +265,64 @@ describe Hashie::Trash do
       expect(subject.first_name).to eq('Frodo')
     end
   end
+
+  context 'when copying properties from other properties' do
+    it 'retains the original and also sets the copy' do
+      simple = Class.new(Hashie::Trash) do
+        property :id
+        property :copy_of_id, from: :id
+      end
+
+      subject = simple.new(id: 1)
+
+      expect(subject.id).to eq(1)
+      expect(subject.copy_of_id).to eq(1)
+    end
+
+    it 'grabs the default for the original if it is not set' do
+      with_default = Class.new(Hashie::Trash) do
+        property :id, default: 0
+        property :copy_of_id, from: :id
+      end
+
+      subject = with_default.new
+
+      expect(subject.id).to eq(0)
+      expect(subject.copy_of_id).to eq(0)
+    end
+
+    it 'can be a required value' do
+      with_required = Class.new(Hashie::Trash) do
+        property :id
+        property :copy_of_id, from: :id, required: true, message: 'must be set'
+      end
+
+      expect { with_required.new }.to raise_error(ArgumentError, "The property 'copy_of_id' must be set")
+    end
+
+    it 'does not set properties that do not exist' do
+      from_non_property = Class.new(Hashie::Trash) do
+        property :copy_of_value, from: :value
+      end
+
+      subject = from_non_property.new(value: 0)
+
+      expect(subject).not_to respond_to(:value)
+      expect { subject[:value] }.to raise_error(NoMethodError, "The property 'value' is not defined for .")
+      expect(subject.to_h[:value]).to eq(nil)
+      expect(subject.copy_of_value).to eq(0)
+    end
+
+    it 'is not order-dependent in definition' do
+      simple = Class.new(Hashie::Trash) do
+        property :copy_of_id, from: :id
+        property :id
+      end
+
+      subject = simple.new(id: 1)
+
+      expect(subject.id).to eq(1)
+      expect(subject.copy_of_id).to eq(1)
+    end
+  end
 end