Proper single-table inheritance support for Audit#revision

lib/audited/audit.rb

@@ -64,9 +64,18 @@ def ancestors
     # the object has been destroyed, this will be a new record.
     def revision
       clazz = auditable_type.constantize
-      (clazz.find_by_id(auditable_id) || clazz.new).tap do |m|
-        self.class.assign_revision_attributes(m, self.class.reconstruct_attributes(ancestors).merge(version: version))
-      end
+      attributes = self.class.reconstruct_attributes(ancestors).merge(version: version)
+      inheritance_column = clazz.inheritance_column.to_s
+
+      instance = if clazz.exists?(id: auditable_id)
+                   clazz.find_by_id(auditable_id)
+                 elsif attributes.key?(inheritance_column)
+                   clazz.new(inheritance_column => attributes.delete(inheritance_column))
+                 else
+                   clazz.new
+                 end
+
+      self.class.assign_revision_attributes(instance, attributes)
     end
 
     # Returns a hash of the changed attributes with the new values

lib/audited/auditor.rb

@@ -24,7 +24,7 @@ module ClassMethods
       # * +except+ - Excludes fields from being saved in the audit log.
       #   By default, Audited will audit all but these fields:
       #
-      #     [self.primary_key, inheritance_column, 'lock_version', 'created_at', 'updated_at']
+      #     [self.primary_key, 'lock_version', 'created_at', 'updated_at']
       #   You can add to those by passing one or an array of fields to skip.
       #
       #     class User < ActiveRecord::Base
@@ -79,7 +79,7 @@ def has_associated_audits
       end
 
       def default_ignored_attributes
-        [primary_key, inheritance_column]
+        [primary_key]
       end
     end
 

spec/audited/audit_spec.rb

@@ -124,6 +124,26 @@ class TempModel < ::ActiveRecord::Base
       expect(revision.name).to eq(user.name)
       expect(revision).to be_a_new_record
     end
+
+    context "single-table inheritance" do
+      it "should return the right subclass for existing records" do
+        sti_company = Models::ActiveRecord::Company::STICompany.create
+        revision = sti_company.audits.last.revision
+        expect(revision).to be_a(Models::ActiveRecord::Company::STICompany)
+      end
+
+      it "should return the right subclass for deleted records" do
+        sti_company = Models::ActiveRecord::Company::STICompany.create
+        sti_company.destroy
+        revision = sti_company.audits.last.revision
+
+        if Models::ActiveRecord::Company::STICompany.respond_to?(:attr_accessible)
+          expect(revision).to be_a(Models::ActiveRecord::Company)
+        else
+          expect(revision).to be_a(Models::ActiveRecord::Company::STICompany)
+        end
+      end
+    end
   end
 
   it "should set the version number on create" do

spec/audited/auditor_spec.rb

@@ -4,11 +4,11 @@
 
   describe "configuration" do
     it "should include instance methods" do
-      expect(Models::ActiveRecord::User.new).to be_a_kind_of( Audited::Auditor::AuditedInstanceMethods)
+      expect(Models::ActiveRecord::User.new).to be_a_kind_of(Audited::Auditor::AuditedInstanceMethods)
     end
 
     it "should include class methods" do
-      expect(Models::ActiveRecord::User).to be_a_kind_of( Audited::Auditor::AuditedClassMethods )
+      expect(Models::ActiveRecord::User).to be_a_kind_of(Audited::Auditor::AuditedClassMethods )
     end
 
     ['created_at', 'updated_at', 'created_on', 'updated_on', 'lock_version', 'id', 'password'].each do |column|
@@ -17,6 +17,12 @@
       end
     end
 
+    context "single-table inheritance record" do
+      it "should audit type to retrieve object revisions without loosing inheritance information" do
+        expect(Models::ActiveRecord::Company::STICompany.non_audited_columns).not_to include('type')
+      end
+    end
+
     it "should be configurable which attributes are not audited via ignored_attributes" do
       Audited.ignored_attributes = ['delta', 'top_secret', 'created_at']
       class Secret < ::ActiveRecord::Base