if params[:search_me]
     @persons = Person.search_me(params[:search_me]).order(sort_column + ' ' + sort_direction).paginate(:per_page => 5, :page => params[:page])
else
 @persons = Person.select('persons.*, count(participants.person_id) AS participant_count').joins(:participants).group('participants.person_id').order('participant_count desc').paginate(:per_page => 30, :page => params[:page]).order(sort_column + ' ' + sort_direction)
end

private

def sort_column
   Person.column_names.include?(params[:sort]) ? params[:sort] : "prename"
end

def sort_direction
   %w[asc desc].include?(params[:direction]) ? params[:direction] : "asc"
end

<%= will_paginate @persons, :previous_label => t("previous_label"), :next_label => t("next_label"), :page_gap => t("will_paginate.page_gap")%>