如何在angular 5的ng多选下拉菜单中添加文本字段或html

<ng-template #customOption let-option="option">
  <span>{{ option.label }}</span>
  <input type="text" [(ngModel)]="option.customText">
</ng-template>

import { Component } from '@angular/core';

@Component({
  selector: 'app-dropdown',
  templateUrl: './dropdown.component.html',
  styleUrls: ['./dropdown.component.css']
})
export class DropdownComponent {
  options = [
    { label: 'Option 1', value: 1, customText: '' },
    { label: 'Option 2', value: 2, customText: '' },
    { label: 'Option 3', value: 3, customText: '' }
  ];
}

<ng-select [items]="options" [multiple]="true" [closeOnSelect]="false" [virtualScroll]="true" [itemValueField]="'value'" [itemTextField]="'label'">
  <ng-template ng-option-tmp let-item="item" let-index="index" let-search="searchTerm">
    <input type="checkbox" [ngModel]="item.selected" (ngModelChange)="item.selected = $event">
    <ng-container *ngTemplateOutlet="customOption; context: { option: item }"></ng-container>
  </ng-template>
</ng-select>