1 files changed, 24 insertions, 0 deletions
diff --git a/activesupport/lib/active_support/core_ext/hash/except.rb b/activesupport/lib/active_support/core_ext/hash/except.rb
new file mode 100644
index 0000000000..8362cd880e
--- /dev/null
+++ b/activesupport/lib/active_support/core_ext/hash/except.rb
@@ -0,0 +1,24 @@
+require 'set'
+
+module ActiveSupport #:nodoc:
+  module CoreExtensions #:nodoc:
+    module Hash #:nodoc:
+      # Return a hash that includes everything but the given keys. This is useful for
+      # limiting a set of parameters to everything but a few known toggles:
+      #
+      #   @person.update_attributes(params[:person].except(:admin))
+      module Except
+        # Returns a new hash without the given keys.
+        def except(*keys)
+          rejected = Set.new(respond_to?(:convert_key) ? keys.map { |key| convert_key(key) } : keys)
+          reject { |key,| rejected.include?(key) }
+        end
+
+        # Replaces the hash without only the given keys.
+        def except!(*keys)
+          replace(except(*keys))
+        end
+      end
+    end
+  end
+end