如何在Dart Polymer中使用和迭代可观察的地图？ [英] How to use and to iterate an observable map in Dart Polymer?

问题描述

请考虑以下代码：

myexample.html

 < polymer-element name =my-example> 
< script type =application / dartsrc =myexample.dart>< / script> 
< template> 
< style>< / style> 
< div> 
< ul> 
< template repeat ={{map invalues}}> 
< li> {{entry}}< / li> 
< / template> 
< / ul> 
< button on-click ={{add}}>添加< / button> 
< / div> 
< / template> 
< / polymer-element> 
  

myexample.dart

$ b b< b>< int>< int>< int> map = toObservable（{}）;
int i = 0;

MyExample.created（）：super.created（）;

void add（）{
map [i ++] = i.toString（）;
}
}

按钮，但映射条目不会显示在myexample.html中。所以：如何正确地使用（和迭代）可观察映射，以便html文件中的列表自动更新？

解决方案

这是一个错误。我刚刚提出：

https://code.google.com/p/dart/issues/detail?id=15407

请将问题标上星号，以便您可以在修复错误时通知。

Consider the following code:

myexample.html

<polymer-element name="my-example">
  <script type="application/dart" src="myexample.dart"></script>
  <template>
    <style></style>
    <div>
    <ul>
        <template repeat="{{ entry in map.values }}">
          <li>{{ entry }}</li>
        </template>
    </ul>
    <button on-click="{{add}}">Add</button>
    </div>
  </template>
</polymer-element>

myexample.dart

@CustomTag('my-example')
class MyExample extends PolymerElement {
  @observable Map<int, String> map = toObservable({});
  int i = 0;

  MyExample.created() : super.created();

  void add() {
    map[i++] = i.toString();
  }
}

The map is filled on every click of the "Add" button, but the map-entries aren't shown in myexample.html. So: How to use (and to iterate) an observable Map properly, such that the list in the html-file is updated automatically?

解决方案

This is a bug. I just filed it:

https://code.google.com/p/dart/issues/detail?id=15407

Please star the issue so that you can be notified when the bug is fixed.

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