Question

看来我曾经工作的Polymer Dart自定义元素现在停止了射击。 Dartium在localhost中显示h1标签，但不显示我的自定义元素。

我得到的唯一Dart编辑器错误/警告是：

"(from html5lib) Unexpected start tag (link). Expected DOCTYPE. See http://goo.gl/5HPeuP#polymer_40 for details."

每条

都会显示此警告消息

 <link rel="import" href="packages/polymer/polymer.html">

但最好的我可以看到这是一个已知问题，不应妨碍应用程序的执行。

我迄今为止的故障排除工作包括： - 从命令行运行pub cache cache - 手动删除包缓存目录并再次运行pub。 - 下载并运行polymer-and-dart-codelab-master.zip（我得到相同的行为）

如何诊断此问题？

Pubspec.yaml内容：

name: mpower
description: Sample app built with the polymer.dart package
environment:
  sdk: '>=1.2.0 <2.0.0'
dependencies:
  polymer: '>=0.15.1 <0.16.0'
dev_dependencies:
  unittest: '>=0.10.0 <0.11.0'
transformers:
- polymer:
    entry_points:
    - web/index.html

Index.html内容：

<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Mosaic mPower</title>
    <link rel="import" href="est_list.html">
    <link rel="stylesheet" href="app.css">
  </head>
  <body>
    <h1>Mosaic mPower</h1>
    <est-list></est-list>
    <script type="application/dart">export 'package:polymer/init.dart';</script>
  </body>
</html>

EST-list.html

<link rel="import" href="packages/polymer/polymer.html">
<link rel="import" href="est_form.html">
<link rel="import" href="est_element.html">

<polymer-element name="est-list">
  <template>
    <style>
     select {
       margin-bottom: 30px;
       display: inline;
       padding: 6px 12px;
       font-size: 14px;
       line-height: 1.42857143;
       color: #555;
       background-color: #fff;
       background-image: none;
       border: 1px solid #ccc;
       border-radius: 2px;
       -webkit-box-shadow: inset 0 1px 1px rgba(0,0,0,.075);
       box-shadow: inset 0 1px 1px rgba(0,0,0,.075);
       -webkit-transition: border-color ease-in-out .15s,box-shadow ease-in-out .15s;
       transition: border-color ease-in-out .15s,box-shadow ease-in-out .15s;
     }
   </style>
   <div>
     <label>Filter: </label>
     <select value="{{filterValue}}" on-change="{{filter}}">
       <option template repeat="{{filter in filters}}">
         {{filter}}
       </option>
     </select>
   </div>
   <div on-estvalidated="{{addEst}}"
        on-formnotneeded="{{resetForm}}">
     <est-form est="{{newEst}}"></est-form>
   </div>
   <div on-deleteest="{{deleteEst}}"
        on-levelchanged="{{filter}}">
     <template repeat="{{est in filteredEsts}}">
       <est-element est="{{est}}"></est-element>
     </template>
   </div>
 </template>
 <script type="application/dart" src="est_list.dart"></script>

EST-list.dart

import 'package:polymer/polymer.dart';
import 'model.dart' show Est;
import 'dart:html' show Event, Node;

/*
 * Class to represent a collectionon-est of Est objects.
 */
@CustomTag('est-list')
class EstList extends PolymerElement {
  static const ALL = "all";
  /*
   * Field for a new Est object.
   */
  @observable Est newEst = new Est();

  /*
   * Collection of ests. The source of truth for all ests in this app.
   */
  @observable List<Est> ests = toObservable([]);

  /*
   * Sets the new est form to default to the intermediate level.
   */
  String get defaultCustomer => Est.CUSTOMERS[0];

  /*
   * List of filter values. Includes the levels defined in the model, as well
   * as a filter to return all ests.
   */
  final List<String> filters = [ALL]..addAll(Est.CUSTOMERS);

  /*
   * String that stores the value used to filter ests.
   */
  @observable String filterValue = ALL;

  /*
   * The list of filtered ests.
   */
  @observable List<Est> filteredEsts = toObservable([]);

  /*
   * Named constructor. Sets initial value of filtered ests and sets
   * the new est's customer to the default.
   */
  EstList.created() : super.created() {
    filteredEsts = ests;
    newEst.customer = defaultCustomer;
  }

  /*
   * Replaces the existing new Est, causing the new est form to reset.
   */
  resetForm() {
    newEst = new Est();
    newEst.customer = defaultCustomer;
  }

  /*
   * Adds a est to the ests list and resets the new est form. This
   * triggers estsChanged().
   */
  addEst(Event e, var detail, Node sender) {
    e.preventDefault();
    ests.add(detail['est']);
    resetForm();
  }

  /*
   * Removes a est from the ests list. This triggers estsChanged().
   */
  deleteEst(Event e, var detail, Node sender) {
    var est = detail['est'];
    ests.remove(est);
  }

  /*
   * Calculates the ests to display when using a filter.
   */
  filter() {
    if (filterValue == ALL) {
      filteredEsts = ests;
      return;
    }
    filteredEsts = ests.where((est) {
      return est.customer == filterValue;
    }).toList();
  }

  /*
   * Refreshes the filtered ests list every time the ests list changes.
   */
  estsChanged() {
    filter();
  }
}

Answer 1

如评论中所述，这是由过期的Dartium造成的。

可悲的是，它没有显示消息来讲述它。明确这个未解决的问题http://dartbug.com/18560以获取更新。

Polymer Dart Custom Element未执行

1 个答案: