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How can I get an instance to the paper-input element below?
HTML file:
<!DOCTYPE html>
<html>
<head>
<!-- <script src='packages/web_components/platform.js'></script>
not necessary anymore with Polymer >= 0.14.0 -->
<script src='packages/web_components/dart_support.js'></script>
<link rel='import' href='packages/paper_elements/paper_input.html'>
<script src='packages/browser/dart.js'></script>
</head>
<body fullbleed unresolved>
<paper-input id='subject' label='subject'></paper-input>
<script type='application/dart' src='myscript.dart'></script>
</body>
</html>
myscript.dart:
import 'dart:html';
import 'package:polymer/polymer.dart';
import 'package:paper_elements/paper_input.dart';
export 'package:polymer/init.dart';
PaperInput _subject = querySelector('#subject'); // exception
void main() {
...
}
This causes an exception:
Breaking on exception: type 'HtmlElement' is not a subtype of type 'PaperInput'
Casting from HtmlElement to PaperInput does not work. Suggestions have included using shadowRoot.querySelector('#subject'); and other shadowRoot usages, but where does it come from? If I append .shadowRoot.querySelector('paper-input') to the last line of myscript.dart, the element is null. Same result if I use the id instead of tag name. The element itself is top-level to the html body, so it is not in any other shadowRoot.
There is no way to get the contents of the paper-input without it being of the class PaperInput. But there seems no way to cast it.
You run into how to implement a main function in polymer apps
When you do it like shown below or inside a Polymer element (
attached()aftersuper.attached()or in some click or other event handler (when the element is properly initialized)