René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Missing forwardRef in Query/ViewQuery should throw","articleBody":"Consider the following code\n\n``` javascript\n@Component({selector: 'accordion'})\n@View({\n  template: `\n        \u003caccordion-item\u003e\u003c/accordion-item\u003e\n        \u003caccordion-item\u003e\u003c/accordion-item\u003e`,\n  directives : [forwardRef(() =\u003e AccordionItem)]\n})\nexport class Accordion implements OnInit {\n    constructor(el: ElementRef, @ViewQuery(AccordionItem) items:QueryList\u003cAccordionItem\u003e) {\n          this.items = items;\n    }\n    onInit() {\n         console.log(this.items);\n    }\n}\n\n@Component({selector: 'accordion-item'})\n@View({template: `...`})\nexport class AccordionItem {}\n```\n\nThis works, but `items` returns 0 results, which is wierd since there are two children (see plnkr below). The problem here is a missing `forwardRef`.\n\nIf you remove `forwardRef` from the `directives` property in `Accordion` you'll get this error message. Pretty useful.\n\n```\nUnexpected directive value 'undefined' on the View of component 'Accordion'\n```\n\nBut if you miss `forwardRef` in `@ViewQuery` instead of an error you'll get 0 results, while it should throw a similar error to the above one.\n\nSee [repro](http://plnkr.co/edit/MmRqUP?p=preview), switch between the constructors in `Accordion` class and you'll see that no errors are thrown but the length of the results changes.\n\nPS: The title includes `Query` which I didn't test, but I'm assuming that both works similar.\n","author":{"url":"https://github.com/ericmartinezr","@type":"Person","name":"ericmartinezr"},"datePublished":"2015-09-14T12:52:35.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":4},"url":"https://github.com/4174/angular/issues/4174"}