update attribute_builder for rails change

rails 5.0.7 changed the way attribute_builder works
This updates attribute_builder to work accordingly

Also, 5.0.0 changed the way dirty worked.
Think the change to forgetting_assignment introduced this problem for
all rails versions, but it is subtle and would only be noticed by
people who use lots of non-database attributes (e.g.: us)
It remains in 5.1.0 but the code changes significantly in 5.2

lib/extensions/ar_virtual.rb

@@ -400,12 +400,15 @@ def virtual_attribute_names
       end
     end
 
-    def attributes_builder
-      @attributes_builder ||= ::ActiveRecord::AttributeSet::Builder.new(attribute_types, primary_key) do |name|
-        unless columns_hash.key?(name) || virtual_attribute?(name)
-          _default_attributes[name].dup
-        end
+    def attributes_builder # :nodoc:
+      unless defined?(@attributes_builder) && @attributes_builder
+        defaults = _default_attributes.except(*(column_names - [primary_key]))
+        # change necessary for rails 5.0 and 5.1 - (changed/introduced in https://github.com/rails/rails/pull/31894)
+        defaults = defaults.except(*virtual_attribute_names)
+        # end change
+        @attributes_builder = ActiveRecord::AttributeSet::Builder.new(attribute_types, defaults)
       end
+      @attributes_builder
     end
 
     private
@@ -597,6 +600,18 @@ def remove_virtual_fields(associations)
 # Class extensions
 #
 
+# this patch is no longer necessary for 5.2
+require "active_record/attribute"
+module ActiveRecord
+  # This is a bug in rails 5.0 and 5.1, but it is made much worse by virtual attributes
+  class Attribute
+    def with_value_from_database(value)
+      # self.class.from_database(name, value, type)
+      initialized? ? self.class.from_database(name, value, type) : self
+    end
+  end
+end
+
 module ActiveRecord
   class Base
     include VirtualFields

spec/lib/extensions/ar_virtual_spec.rb

@@ -981,6 +981,15 @@ def col2
   end
 end
 
+describe "ActiveRecord attributes" do
+  it "doesn't botch up the attributes" do
+    hardware = Hardware.select(:id, :model).find(FactoryGirl.create(:hardware).id)
+    expect(hardware.attributes.size).to eq(2)
+    hardware.save
+    expect(hardware.attributes.size).to eq(2)
+  end
+end
+
 describe "ApplicationRecord class" do
   describe ".virtual_attribute_names" do
     it "class immediately under ApplicationRecord" do