1 files changed, 37 insertions, 0 deletions
diff --git a/activerecord/lib/active_record/types/unknown.rb b/activerecord/lib/active_record/types/unknown.rb
new file mode 100644
index 0000000000..f832c7b304
--- /dev/null
+++ b/activerecord/lib/active_record/types/unknown.rb
@@ -0,0 +1,37 @@
+module ActiveRecord
+  module Type
+    # Useful for handling attributes not mapped to types. Performs some boolean typecasting,
+    # but otherwise leaves the value untouched.
+    class Unknown
+
+      def cast(value)
+        value
+      end
+
+      def precast(value)
+        value
+      end
+
+      # Attempts typecasting to handle numeric, false and blank values.
+      def boolean(value)
+        empty = (numeric?(value) && value.to_i.zero?) || false?(value) || value.blank?
+        !empty
+      end
+
+      def appendable?
+        false
+      end
+
+      protected
+
+      def false?(value)
+        ActiveRecord::ConnectionAdapters::Column::FALSE_VALUES.include?(value)
+      end
+
+      def numeric?(value)
+        Numeric === value || value !~ /[^0-9]/
+      end
+
+    end
+  end
+end
+\ No newline at end of file