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Should only fire output property once even if both in [outputs] and decorated w/ @Output #4798
Description
Consider this component:
@Component({
selector: 'hero-detail',
inputs: ['hero'],
outputs: ['deleted'],
template: `
<div>
<b>Hero Detail: {{hero?.fullName}}</b>
<button (click)="onDelete()">Delete</button>
</div>
`
})
class HeroDetailComponent {
@Input()
hero: Hero;
@Output()
deleted = new EventEmitter();
onDelete() {
this.deleted.next(this.hero);
}
}
Now we bind to it:
<hero-detail [hero]="currentHero" (deleted)="onDeleted($event)"></hero-detail>
When the user clicks the Delete button inside <hero-detail>, the parent's onDeleted method is called twice.
Remove either the [outputs] array or the @Output decoration and the parent's method is called only once.
The number of parent method calls increase by one for each additional @Output decoration.
I maintain that any number of mentions as an output > 1 should still mean a single call to the parent method.
Activity
[-]Should only fire output property once even when list both in [outputs] and w/ @Output[/-][+]Should only fire output property once even if both in [outputs] and decorated w/ @Output[/+]ericmartinezr commentedon Oct 17, 2015
FWIW this was reported a few days ago, but it was closed immediatly #4611
jessegood commentedon Oct 17, 2015
Is there a use case for having both? I would consider this a mistake in the code and would like the framework to tell me by throwing an exception.
mhevery commentedon Oct 22, 2015
I think we should throw an error when the same event is registered more then once.
wardbell commentedon Oct 24, 2015
That's ok too. I'm more of a "be tolerant in what you accept person" myself but that policy can lead us into trouble and maybe it would here. Lets do something😊
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