Subclasses of an abstract class work with single-table inheritance. References #5704, closes #7284.

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@6013 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

4 files changed, 21 insertions, 3 deletions

diff --git a/activerecord/CHANGELOG b/activerecord/CHANGELOG
index de3a777920..d3d0b3d510 100644
--- a/activerecord/CHANGELOG
+++ b/activerecord/CHANGELOG
@@ -1,5 +1,7 @@
 *SVN*
 
+* Subclasses of an abstract class work with single-table inheritance.  #5704, #7284 [BertG, nick+rails@ag.arizona.edu]
+
 * Make sure sqlite3 driver closes open connections on disconnect [Rob Rasmussen]
 
 * [DOC] clear up some ambiguity with the way has_and_belongs_to_many creates the default join table name.  #7072 [jeremymcanally]
diff --git a/activerecord/lib/active_record/base.rb b/activerecord/lib/active_record/base.rb
index a783feafed..b8a497ffa3 100755
--- a/activerecord/lib/active_record/base.rb
+++ b/activerecord/lib/active_record/base.rb
@@ -817,8 +817,13 @@ module ActiveRecord #:nodoc:
         attribute_key_name.humanize
       end
 
-      def descends_from_active_record? # :nodoc:
-        superclass == Base || !columns_hash.include?(inheritance_column)
+      # True if this isn't a concrete subclass needing a STI type condition.
+      def descends_from_active_record?
+        if superclass.abstract_class?
+          superclass.descends_from_active_record?
+        else
+          superclass == Base || !columns_hash.include?(inheritance_column)
+        end
       end
 
 
diff --git a/activerecord/test/fixtures/company.rb b/activerecord/test/fixtures/company.rb
index c012a978a0..ff92b14fcb 100755
--- a/activerecord/test/fixtures/company.rb
+++ b/activerecord/test/fixtures/company.rb
@@ -1,4 +1,8 @@
-class Company < ActiveRecord::Base
+class AbstractCompany < ActiveRecord::Base
+  self.abstract_class = true
+end
+
+class Company < AbstractCompany
   attr_protected :rating
   set_sequence_name :companies_nonstd_seq
 
diff --git a/activerecord/test/inheritance_test.rb b/activerecord/test/inheritance_test.rb
index 8b0d70cfa3..7ab1d91061 100755
--- a/activerecord/test/inheritance_test.rb
+++ b/activerecord/test/inheritance_test.rb
@@ -6,6 +6,13 @@ require 'fixtures/subscriber'
 class InheritanceTest < Test::Unit::TestCase
   fixtures :companies, :projects, :subscribers, :accounts
 
+  def test_company_descends_from_active_record
+    assert_raise(NoMethodError) { ActiveRecord::Base.descends_from_active_record? }
+    assert AbstractCompany.descends_from_active_record?, 'AbstractCompany should descend from ActiveRecord::Base'
+    assert Company.descends_from_active_record?, 'Company should descend from ActiveRecord::Base'
+    assert !Class.new(Company).descends_from_active_record?, 'Company subclass should not descend from ActiveRecord::Base'
+  end
+
   def test_a_bad_type_column
     #SQLServer need to turn Identity Insert On before manually inserting into the Identity column
     if current_adapter?(:SQLServerAdapter, :SybaseAdapter)