1 files changed, 23 insertions, 0 deletions
diff --git a/activemodel/lib/active_model/mass_assignment_security/sanitizer.rb b/activemodel/lib/active_model/mass_assignment_security/sanitizer.rb
new file mode 100644
index 0000000000..150beb1ff2
--- /dev/null
+++ b/activemodel/lib/active_model/mass_assignment_security/sanitizer.rb
@@ -0,0 +1,23 @@
+module ActiveModel
+  module MassAssignmentSecurity
+    module Sanitizer
+      # Returns all attributes not denied by the authorizer.
+      def sanitize(attributes)
+        sanitized_attributes = attributes.reject { |key, value| deny?(key) }
+        debug_protected_attribute_removal(attributes, sanitized_attributes)
+        sanitized_attributes
+      end
+
+    protected
+
+      def debug_protected_attribute_removal(attributes, sanitized_attributes)
+        removed_keys = attributes.keys - sanitized_attributes.keys
+        warn!(removed_keys) if removed_keys.any?
+      end
+
+      def warn!(attrs)
+        self.logger.debug "WARNING: Can't mass-assign protected attributes: #{attrs.join(', ')}" if self.logger
+      end
+    end
+  end
+end