[krasovsky]

<span class="sub-heading" id="user_edit_position"><span ng-if="user_name">{{user_name}} </span><span ng-if="user_last_name">{{user_last_name}} </span><span ng-if="user_last_name">{{user_father_name}}</span></span>

Вместо ng-if возможно нужно ng-show