ParameterCleaner

Strips angle brackets from user input on the way into the application, providing an extra level of security against XSS attacks even when someone forgets an h() in a template.

This is not a replacement for proper escaping!

Exclusions

Password fields (anything matching /password/) are not stripped. For one thing, users should be allowed to make strong passwords; for another, you’re never going to display them in the application. Right?

For fields where you want to allow angle brackets, you can disable it on a parameter-by-parameter basis:

class SomeController < ApplicationController
  do_not_clean_param [:thing, :html_description]
end

The array corresponds to the hash keys used to get to the parameter; there is no distinction between string parameters and array parameters.

Form parameter  |  do_not_clean_param
----------------+--------------------
foo             |  [:foo] or :foo
foo[bar]        |  [:foo, :bar]
foo[bar][]      |  [:foo, :bar]

You can specify multiple parameters in one line:

do_not_clean_param :foo, :bar, [:nested, :baz]