I am trying to learn Angular 2.
I would like to access to a child component from a parent component using the @ViewChild Annotation.
Here some lines of code:
In BodyContent.ts I have:
import {ViewChild, Component, Injectable} from 'angular2/core';
import {FilterTiles} from '../Components/FilterTiles/FilterTiles';
@Component({
selector: 'ico-body-content'
, templateUrl: 'App/Pages/Filters/BodyContent/BodyContent.html'
, directives: [FilterTiles]
})
export class BodyContent {
@ViewChild(FilterTiles) ft:FilterTiles;
public onClickSidebar(clickedElement: string) {
console.log(this.ft);
var startingFilter = {
title: 'cognomi',
values: [
'griffin'
, 'simpson'
]}
this.ft.tiles.push(startingFilter);
}
}
while in FilterTiles.ts:
import {Component} from 'angular2/core';
@Component({
selector: 'ico-filter-tiles'
,templateUrl: 'App/Pages/Filters/Components/FilterTiles/FilterTiles.html'
})
export class FilterTiles {
public tiles = [];
public constructor(){};
}
Finally here the templates (as suggested in comments):
BodyContent.html
<div (click)="onClickSidebar()" class="row" style="height:200px; background-color:red;">
<ico-filter-tiles></ico-filter-tiles>
</div>
FilterTiles.html
<h1>Tiles loaded</h1>
<div *ngFor="#tile of tiles" class="col-md-4">
... stuff ...
</div>
FilterTiles.html template is correctly loaded into ico-filter-tiles tag (indeed I am able to see the header).
Note: the BodyContent class is injected inside another template (Body) using DynamicComponetLoader: dcl.loadAsRoot(BodyContent, '#ico-bodyContent', injector):
import {ViewChild, Component, DynamicComponentLoader, Injector} from 'angular2/core';
import {Body} from '../../Layout/Dashboard/Body/Body';
import {BodyContent} from './BodyContent/BodyContent';
@Component({
selector: 'filters'
, templateUrl: 'App/Pages/Filters/Filters.html'
, directives: [Body, Sidebar, Navbar]
})
export class Filters {
constructor(dcl: DynamicComponentLoader, injector: Injector) {
dcl.loadAsRoot(BodyContent, '#ico-bodyContent', injector);
dcl.loadAsRoot(SidebarContent, '#ico-sidebarContent', injector);
}
}
The problem is that when I try to write ft
into the console log, I get undefined
, and of course I get an exception when I try to push something inside the "tiles" array: 'no property tiles for "undefined"'.
One more thing: FilterTiles component seems to be correctly loaded, since I'm able to see the html template for it.
Any suggestion? Thanks
I had a similar issue and thought I'd post in case someone else made the same mistake. First, one thing to consider is AfterViewInit
; you need to wait for the view to be initialized before you can access your @ViewChild
. However, my @ViewChild
was still returning null. The problem was my *ngIf
. The *ngIf
directive was killing my controls component so I couldn't reference it.
import {Component, ViewChild, OnInit, AfterViewInit} from 'angular2/core';
import {ControlsComponent} from './controls/controls.component';
import {SlideshowComponent} from './slideshow/slideshow.component';
@Component({
selector: 'app',
template: `
<controls *ngIf="controlsOn"></controls>
<slideshow (mousemove)="onMouseMove()"></slideshow>
`,
directives: [SlideshowComponent, ControlsComponent]
})
export class AppComponent {
@ViewChild(ControlsComponent) controls:ControlsComponent;
controlsOn:boolean = false;
ngOnInit() {
console.log('on init', this.controls);
// this returns undefined
}
ngAfterViewInit() {
console.log('on after view init', this.controls);
// this returns null
}
onMouseMove(event) {
this.controls.show();
// throws an error because controls is null
}
}
Hope that helps.
EDIT
As mentioned by @Ashg below, a solution is to use @ViewChildren
instead of @ViewChild
.