Rails 3 active class navigation helper which by default takes query params into account.

active_link_to.rb

# application_helper.rb
# Dynamically set the current navigation item to "active".
# Takes query params into account by default. 
# Passing in nil for query_params ignores query params.
# Based on http://stackoverflow.com/a/8552816/545017

# Returns true when path is the active (current) path
def active_path?(path, include_query_params = true)
  if include_query_params
    current_params = params.keep_if { |key, value| !["action", "controller", "id"].include? key }
    query_params = path =~ /\?/ ? Rack::Utils.parse_nested_query(path.split("?").last) : {}
    (current_page?(path) && query_params == current_params)
  else
    current_page?(path)
  end
end

# Extends link_to, injects "active" css class when href is active
def active_link_to(*args, &block)
  path = block ? args[0] : args[1]
  html_options = args.last.is_a?(Hash) ? args.pop.symbolize_keys : {}
  inject_active_class(html_options) if active_path?(path)
  args << html_options
  link_to(*args, &block)
end

# See active_link_to
def inject_active_class(html_options)
  html_options[:class] = html_options.has_key?(:class) ? html_options.delete(:class) + ' active' : 'active'
  html_options
end

# See active_li_link_to
def active_class_if_current(path)
  {class: "active"} if active_path?(path)
end

# Haml active_li_link_to. Returns link wrapped in li tag. 
# Sets li & a class to "active" when href path is active.
def active_li_link_to(*args, &block)
  path = block ? args[0] : args[1]
  haml_tag :li, active_class_if_current(path) do
    haml_concat(active_link_to(*args, &block))
  end
end

navigation.html.haml

%ul.nav.nav-pills
  - active_li_link_to "Suppliers", companies_path(type: 'supplier')
  - active_li_link_to "Customers", companies_path(status: 'customer')
  - active_li_link_to "All Companies", Companies_path