I am trying to make a Joomla menu more accessible. I am using Bootstrap 3 and letting Joomla generate the menu and dropdowns but I need to add ' data-toggle="dropdown" role="button" aria-haspopup="true" aria-expanded="false" ' to the top level href among some other aria elements (See example below). However cannot figure out how to use the template overrides to input the information I need. I would prefer not to have to code the menu manually but I will if I have too.
<ul class="nav navbar-nav" >
<li class="dropdown">
<a href="#"
id="toplevelitem"
class="dropdown-toggle"
data-toggle="dropdown"
role="button"
aria-haspopup="true"
aria-expanded="false"
>
Top Level Item
<span class="caret"></span></a>
<ul class="dropdown-menu" role="menu" aria-labelledby="toplevelitem">
<li role="presentation"><a role="menuitem" href="#">Item 1</a></li>
<li role="presentation"><a role="menuitem" href="#">Item 2</a></li>
<li role="presentation"><a role="menuitem" href="#">Item 3</a></li>
</ul>
</li>
</ul>