Package as gem

.gitignore

@@ -0,0 +1,3 @@
+.idea
+*.iml
+Gemfile.lock

Gemfile

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+source 'https://rubygems.org'
+
+gem 'rspec', '~> 3.4.0'
+gem 'activerecord', '~> 4.2.0'
+gem 'mysql2', '~> 0.4.3'

README.md

@@ -0,0 +1,16 @@
+# activerecord_merge
+## Simple merge for ActiveRecord objects and their associations
+
+### Installation
+```
+gem install activerecord_merge
+```
+
+### Usage in Rails
+Create `config/initializers/activerecord_merge.rb` with the following line of code
+```
+require 'merge'
+```
+
+### More info
+See [http://ewout.name/2010/04/generic-deep-merge-for-activerecord](http://ewout.name/2010/04/generic-deep-merge-for-activerecord)

activerecord_merge.gemspec

@@ -0,0 +1,12 @@
+Gem::Specification.new do |s|
+  s.name        = 'activerecord_merge'
+  s.version     = '1.0.0'
+  s.date        = '2016-03-07'
+  s.summary     = 'ActiveRecord object merge'
+  s.description = 'Simple merge for ActiveRecord objects and their associations.'
+  s.authors     = ['Ewout Van Troostenberghe']
+  s.files       = ['lib/merge.rb']
+  s.homepage    =
+    'http://rubygems.org/gems/activerecord_merge'
+  s.license = 'MIT'
+end

lib/merge.rb

@@ -1,36 +1,35 @@
 module Merge
-
   # True if self is safe to merge with +object+, ie they are more or less equal.
   # Default implementation compares all attributes except id and metadata.
   # Can be overridden in specific models that have a neater way of comparison.
   def merge_equal?(object)
-    object.instance_of?(self.class) and merge_attributes == object.merge_attributes
+    object.instance_of?(self.class) && merge_attributes == object.merge_attributes
   end
-  
+
   MERGE_INDIFFERENT_ATTRIBUTES = %w(id position created_at updated_at creator_id updater_id).freeze
   MERGE_EXCLUDE_ASSOCIATIONS = [].freeze
-  
+
   # Attribute hash used for comparison.
   def merge_attributes
     merge_attribute_names.inject({}) do |attrs, name|
       attrs[name] = self[name]
       attrs
     end
   end
-  
+
   # Names of the attributes that should be merged.
   def merge_attribute_names
     attribute_names - MERGE_INDIFFERENT_ATTRIBUTES
   end
-  
-  # Names of associations excluded from the merge. 
+
+  # Names of associations excluded from the merge.
   # Override if the model has multiple scoped associations,
   # that can all be retrieved by a single has_many association.
   def merge_exclude_associations
     MERGE_EXCLUDE_ASSOCIATIONS
   end
-  
-  # Merge this object with the given +objects+. 
+
+  # Merge this object with the given +objects+.
   # This object will serve as the master,
   # blank attributes will be taken from the given objects, in order.
   # All associations to +objects+ will be assigned to +self+.
@@ -42,59 +41,60 @@ def merge!(*objects)
         objects.each do |object|
           if r.macro == :has_one
             other = object.send(r.name)
-            if local and other
+            if local && other
               local.merge!(other)
             elsif other
               send("#{r.name}=", other)
             end
+          # TODO: remove this condition to test has_and_belongs_to_many relations. This condition was only added to raise error
+          elsif r.macro == :has_and_belongs_to_many
+            p 'activerecord_merge: merging objects with has_and_belongs_to_many is currently broken'
           else
             other = object.send(r.name) - local
             # May be better to compare without the primary key attribute instead of setting it.
-            other.each {|o| o[r.foreign_key] = self.id}
-            other.reject! {|o| local.any? {|l| merge_if_equal(l,o) }}
+            other.each { |o| o[r.foreign_key] = id }
+            other.reject! { |o| local.any? { |l| merge_if_equal(l, o) } }
             local << other
           end
         end
       end
-      objects.each {|o| o.reload and o.destroy unless o.new_record?}
+      objects.each { |o| o.reload && o.destroy unless o.new_record? }
     end
   end
-  
+
   def merge_attributes!(*objects)
-    blank_attributes = merge_attribute_names.select {|att| self[att].blank?}
-    until blank_attributes.empty? or objects.empty?
+    blank_attributes = merge_attribute_names.select { |att| self[att].blank? }
+    until blank_attributes.empty? || objects.empty?
       object = objects.shift
       blank_attributes.reject! do |att|
-        if val = object[att] and not val.blank?
+        if val = object[att] and !val.blank?
           self[att] = val
         end
       end
     end
     save!
   end
-  
+
   private
-  
+
   def merge_association_reflections
-    self.class.reflect_on_all_associations.select do |r| 
-      [:has_many, :has_one, :has_and_belongs_to_many].include?(r.macro) and 
-      not r.options[:through] and 
-      not merge_exclude_associations.include?(r.name.to_sym)
+    self.class.reflect_on_all_associations.select do |r|
+      [:has_many, :has_one, :has_and_belongs_to_many].include?(r.macro) &&
+        !r.options[:through] &&
+        !merge_exclude_associations.include?(r.name.to_sym)
     end
   end
-  
+
   def merge_if_equal(master, object)
     if master.merge_equal?(object)
-      master.merge!(object) ; true
+      master.merge!(object); true
     end
   end
-
 end
 
 ActiveRecord::Base.class_eval { include Merge }
 
 # Compatibility with ActiveRecord 2.x
 class ActiveRecord::Reflection::AssociationReflection
-  alias :foreign_key :primary_key_name unless method_defined? :foreign_key
+  alias_method :foreign_key, :primary_key_name unless method_defined? :foreign_key
 end
-

spec/database.yml

@@ -1,6 +1,7 @@
-adapter: mysql
+adapter: mysql2
+encoding: utf8
 database: activerecord_merge_test
 username: root
-password: 
-socket: /opt/local/var/run/mysql5/mysqld.sock
-encoding: utf8
+password:
+host: localhost
+port: 3306