Angular mat-menu in ng-template with ngFor

Question

I'm trying to create an ng-template with ngFor instead of duplicated mat-menus in my html. But I'm having trouble with the menu trigger. I understand it needs to be unique for the trigger to work but I can't seem to do it.

  <ng-template ngFor let-filter let-i="index" [ngForOf]="filters()">
    <button mat-button
            [matMenuTriggerFor]="i"
            #filterMenu="matMenuTrigger">
      {{filter.title | translate}}
 
    </button>

    <mat-menu #i="matMenu">
      <button mat-menu-item
              *ngFor="let option of filter.values"
              [value]="option">
        <span>{{ option }}</span>
      </button>
    </mat-menu>
  </ng-template>

Answer 1

I think you are looking for ng-container, which can be iterated with *ngFor there is no need for ID, we can just pass the template reference directly.

HTML:

<ng-container *ngFor="let filter of filters">
  <button mat-button [matMenuTriggerFor]="i" #filterMenu="matMenuTrigger">
    {{filter.title}}
  </button>

  <mat-menu #i="matMenu">
    <button mat-menu-item *ngFor="let option of filter.values" [value]="option">
      <span>{{ option }}</span>
    </button>
  </mat-menu>
</ng-container>

TS:

import { Component } from '@angular/core';
import { MatMenuModule } from '@angular/material/menu';
import { MatButtonModule } from '@angular/material/button';
import { CommonModule } from '@angular/common';

/**
 * @title Menu positioning
 */
@Component({
  selector: 'menu-position-example',
  templateUrl: 'menu-position-example.html',
  standalone: true,
  imports: [MatButtonModule, MatMenuModule, CommonModule],
})
export class MenuPositionExample {
  filters = [
    {
      title: 'first',
      values: ['one', 'two', 'three', 'four'],
    },
    {
      title: 'second',
      values: ['one', 'two', 'three', 'four'],
    },
    {
      title: 'three',
      values: ['one', 'two', 'three', 'four'],
    },
    {
      title: 'four',
      values: ['one', 'two', 'three', 'four'],
    },
  ];
}

Stackblitz Demo