Angular 12 References/ Core
🍀 Angular References
Oleksa Novyk | GitHub

@ContentChildren

You can use ContentChildren to get the QueryList of elements or directives from the content DOM. Any time a child element is added, removed, or moved, the query list will be updated, and the changes observable of the query list will emit a new value.

Content queries are set before the ngAfterContentInit callback is called.

Example

Here is a simple demonstration of how the ContentChildren decorator can be used.

import {AfterContentInit, ContentChildren, Directive, QueryList} from '@angular/core';
 
@Directive({selector: 'child-directive'})
class ChildDirective {
}
 
@Directive({selector: 'someDir'})
class SomeDir implements AfterContentInit {
  @ContentChildren(ChildDirective) contentChildren: QueryList<ChildDirective>;
 
  ngAfterContentInit() {
    // contentChildren is set
  }
}
Links & Tutorials

Options

@ContentChildren(
  selector: Type<any>|Function|string, 
  opts?: {descendants?: boolean, read?: any},
)

selector#

selector: Type<any>|Function|string

The directive type or the name used for querying.

Supported selectors include:

  • any class with the @Component or @Directive decorator
  • a template reference variable as a string (e.g. query <my-component #cmp></my-component> with @ViewChild('cmp'))
  • any provider defined in the child component tree of the current component (e.g. @ViewChild(SomeService) someService: SomeService)
  • any provider defined through a string token (e.g. @ViewChild('someToken') someTokenVal: any)
  • a TemplateRef (e.g. query <ng-template></ng-template> with @ViewChild(TemplateRef) template;)

opts#

opts?: {descendants?: boolean, read?: any}

Additional options.

  • descendants - include only direct children or all descendants.
  • read - read a different token from the queried elements.