在纸元素下拉列表中检索所选项目

Question

我有以下代码遵循 https://github.com/dart-lang/polymer-core-and-paper-examples/blob/master/web/paper_dropdown.html and https://github.com/dart-lang/polymer-core-and-paper-examples/blob/master/web/paper_dropdown.dart

中的示例

已编辑

.html

<paper-dropdown-menu 
  label='Click to select..' 
  on-core-select='{{onCoreSelectCountryHandler}}'>
  <paper-dropdown class='dropdown'>
    <core-menu id='country' class='menu'>
      <template repeat='{{country in countries}}'>
        <paper-item>{{country.name}}</paper-item>
      </template>
    </core-menu>
  </paper-dropdown>
</paper-dropdown-menu>

.dart

final List<Country> countries = [
  const Country('Afghanistan', 'AF'),
  const Country('Åland Islands', 'AX')];

class Country {
  final String name;
  final String code;
  const Country(this.name, this.code);
}

void onCoreSelectCountryHandler(dom.CustomEvent e, var detail) {
    var detail = new JsObject.fromBrowserObject(e)['detail'];

  if (detail['isSelected']) {
  // DOES NOT WORK - HOW DO I GET THE SELECTION ATTEMPTED BELOW
  // The detail should be related to the Country class but 
   // I can't seem to relate it so I could get the selection.
  var kuntry = (detail['item'] as PaperItem).text;

}

如何使用 dart 代码在下拉列表（正常显示）中检索所选元素？

Answer 1

更新

我认为这是最简单的方法

void onCoreSelectCountryHandler(dom.CustomEvent e, var detail) {
  print(countries[$['country'].selected].name);
  // or if you really need to access the `<paper-item>` element
  print(detail['item'].text);
}

旧

paper-dropdown中没有selected。在提供 selected.

的 paper-dropdown 中包裹一个 core-menu

见
- https://www.polymer-project.org/0.5/docs/elements/core-menu.html and the example at https://www.polymer-project.org/0.5/docs/elements/paper-dropdown-menu.html

Answer 2

简单使国家/地区列表可见

final List<Country> cuntries = toObservable[
  const Country('Afghanistan', 'AF'),
  const Country('Åland Islands', 'AX')}]

检索到选择。

我的疏忽。

在纸元素下拉列表中检索所选项目

Retrieving the selected item in a paper-element dropdown

dart

dart-polymer

paper-elements