2 files changed, 13 insertions, 2 deletions
diff --git a/activerecord/lib/active_record/base.rb b/activerecord/lib/active_record/base.rb
index e0bce194b2..2d7cd6c17a 100755
--- a/activerecord/lib/active_record/base.rb
+++ b/activerecord/lib/active_record/base.rb
@@ -28,7 +28,9 @@ module ActiveRecord #:nodoc:
   end
   class ConfigurationError < StandardError #:nodoc:
   end
-
+  class UnknownTypeError < ActiveRecordError #:nodoc:
+  end
+  
   class AttributeAssignmentError < ActiveRecordError #:nodoc:
     attr_reader :exception, :attribute
     def initialize(message, exception, attribute)
@@ -222,6 +224,8 @@ module ActiveRecord #:nodoc:
   #   objects that should be inspected to determine which attributes triggered the errors.
   # * +AttributeAssignmentError+ -- an error occurred while doing a mass assignment through the +attributes=+ method.
   #   You can inspect the +attribute+ property of the exception object to determine which attribute triggered the error.
+  # * +UnknownTypeError+ -- Raised when AbstractAdapter#type_to_sql cannot map the type given to a native type.
+  #
   # *Note*: The attributes listed are class-level attributes (accessible from both the class and instance level).
   # So it's possible to assign a logger to the class through Base.logger= which will then be used by all
   # instances in the current object space.
diff --git a/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb b/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
index f5aa09c1f2..5f9f99b0b2 100755
--- a/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
@@ -431,7 +431,14 @@ module ActiveRecord
       end       
 
       def type_to_sql(type, limit = nil)
-        native = native_database_types[type]
+        unless native = native_database_types[type]
+          raise(
+            ActiveRecord::UnknownTypeError, 
+            "Unable to convert type '#{type}' to a native type. " +
+            "Valid options: #{native_database_types.keys.to_sentence}"
+          )
+        end
+
         limit ||= native[:limit]
         column_type_sql = native[:name]
         column_type_sql << "(#{limit})" if limit