Rails多个复选框--check_box_tag

<% @roles.each do |role| %>  
  <%= check_box_tag ‘roles[]‘, role.id%>  
  <%= label_tag role.name %>  
<% end %>  

<input type="checkbox" value="1" name="roles[]" id="roles_">  
<label for="SuperAdmin">Superadmin</label>  
  
<input type="checkbox" value="2" name="roles[]" id="roles_">  
<label for="Teacher">Teacher</label>  
  
<input type="checkbox" value="3" name="roles[]" id="roles_">  
<label for="Student">Student</label>  

"roles"=>["2", "3"]  #params[:roles]