delegate attribute typecasting to the column

activerecord/lib/active_record/attribute_methods/write.rb

@@ -43,23 +43,9 @@ module ActiveRecord
         end
 
         def type_cast_attribute_for_write(column, value)
-          if column && column.number?
-            convert_number_column_value(value)
-          else
-            value
-          end
-        end
+          return value unless column
 
-        def convert_number_column_value(value)
-          if value == false
-            0
-          elsif value == true
-            1
-          elsif value.is_a?(String) && value.blank?
-            nil
-          else
-            value
-          end
+          column.type_cast_for_write value
         end
     end
   end

activerecord/lib/active_record/connection_adapters/column.rb

@@ -66,6 +66,21 @@ module ActiveRecord
         end
       end
 
+      # Casts a Ruby value to something appropriate for writing to the database.
+      def type_cast_for_write(value)
+        return value unless number?
+
+        if value == false
+          0
+        elsif value == true
+          1
+        elsif value.is_a?(String) && value.blank?
+          nil
+        else
+          value
+        end
+      end
+
       # Casts value (which is a String) to an appropriate instance.
       def type_cast(value)
         return nil if value.nil?