group-selection.component.html

<span class="add-group-selector">
  <ng-select
    [items]="_nodeGroupsList"
    bindLabel="groupName"
    bindValue="groupName"
    [virtualScroll]="true"
    [placeholder]="getAddGroupLabel()"
    (change)="selectGroup($event)"
    pTooltip="Select all nodes of a group."
    [tooltipStyleClass]="'drgstn drgstn-tooltip drgstn-tooltip-right'"
    tooltipPosition="right"
    [clearable]="false"
  >
    <ng-template ng-option-tmp let-item="item">
      <span>{{ item.groupName }}</span>
    </ng-template>
  </ng-select>
</span>