Clashing type columns due to a sloppy join shouldn't wreck single-table inheritance. Closes #5838.

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@4813 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

activerecord/CHANGELOG

@@ -1,5 +1,7 @@
 *SVN*
 
+* Clashing type columns due to a sloppy join shouldn't wreck single-table inheritance.  #5838 [Kevin Clark]
+
 * Fixtures: correct escaping of \n and \r.  #5859 [evgeny.zislis@gmail.com]
 
 * Migrations: gracefully handle missing migration files.  #5857 [eli.gordon@gmail.com]

activerecord/lib/active_record/base.rb

@@ -1027,23 +1027,34 @@ module ActiveRecord #:nodoc:
           end
         end
 
-        # Finder methods must instantiate through this method to work with the single-table inheritance model
-        # that makes it possible to create objects of different types from the same table.
+        # Finder methods must instantiate through this method to work with the
+        # single-table inheritance model that makes it possible to create
+        # objects of different types from the same table.
         def instantiate(record)
-          object = 
+          object =
             if subclass_name = record[inheritance_column]
+              # No type given.
               if subclass_name.empty?
                 allocate
+
               else
                 require_association_class(subclass_name)
-                begin
-                  compute_type(subclass_name).allocate
-                rescue NameError
-                  raise SubclassNotFound,
-                    "The single-table inheritance mechanism failed to locate the subclass: '#{record[inheritance_column]}'. " +
-                    "This error is raised because the column '#{inheritance_column}' is reserved for storing the class in case of inheritance. " +
-                    "Please rename this column if you didn't intend it to be used for storing the inheritance class " +
-                    "or overwrite #{self.to_s}.inheritance_column to use another column for that information."
+
+                # Ignore type if no column is present since it was probably
+                # pulled in from a sloppy join.
+                unless self.columns_hash.include?(inheritance_column)
+                  allocate
+
+                else
+                  begin
+                    compute_type(subclass_name).allocate
+                  rescue NameError
+                    raise SubclassNotFound,
+                      "The single-table inheritance mechanism failed to locate the subclass: '#{record[inheritance_column]}'. " +
+                      "This error is raised because the column '#{inheritance_column}' is reserved for storing the class in case of inheritance. " +
+                      "Please rename this column if you didn't intend it to be used for storing the inheritance class " +
+                      "or overwrite #{self.to_s}.inheritance_column to use another column for that information."
+                  end
                 end
               end
             else

activerecord/test/finder_test.rb

@@ -93,6 +93,11 @@ class FinderTest < Test::Unit::TestCase
     assert_equal(topics(:second).title, topics.first.title)
   end
   
+  def test_find_by_sql_with_sti_on_joined_table
+    accounts = Account.find_by_sql("SELECT * FROM accounts INNER JOIN companies ON companies.id = accounts.firm_id")
+    assert_equal [Account], accounts.collect(&:class).uniq
+  end
+  
   def test_find_first
     first = Topic.find(:first, :conditions => "title = 'The First Topic'")
     assert_equal(topics(:first).title, first.title)