content-children.ts

@Component({
  selector: 'content-component',
  template: '<div>Test {{ data }}</div>',
})
export class ContentComponent {
  @Input() data: string;
}

@Component({
  selector: 'child-component',
  template: '<div>I have {{ childCount }} content children! Data: {{ childData|json }}</div><div><ng-content></ng-content></div>',
})
export class ChildComponent implements AfterContentInit {
  @ContentChildren(ContentComponent) children: QueryList<ContentComponent>;
  childCount: number;
  childData: string[];
  
  ngAfterContentInit() {
    this.childCount = this.children.length;
    this.childData = this.children.map(child => child.data);
  }
}

@Component({
  selector: 'parent-component',
  template: '<child-component><content-component *ngFor="let el of elements" [data]="el"></content-component></child-component>',
})
export class ParentComponent  {
  elements = ['a', 'b', 'c', 'd', 'e'];
}