Dart：@observable的getters [英] Dart: @observable of getters

问题描述

当我绑定隐式getter / setter对'name'时，它会更新

但是显式的getter'fullname'在HTML中没有更新。有一种方法来做这个工作（基本上，元素绑定中的'fullname'也应该更新）。也许我缺少一个setter，但后来setter在这里没有意义...

很简单的例子来证明：

test-element.html

 < ; link rel =importhref =../../ packages / polymer / polymer.html> 
< polymer-element name =test-element> 
< template> 
< input value ={{ds.name}}> 
< div> {{ds.name}}< / div> 
< div> {{ds.fullname}}< / div> 
< / template> 
< script type =application / dartsrc =test1.dart>< / script> 
< / polymer-element> 
  

test-element.dart

  import'package：polymer / polymer.dart'; 
 import'package：popoli / sysmaster-settings.dart'; 
 
 @CustomTag（'test-element'）
 class TestElement extends PolymerElement {
 @observable VerySimpleTest ds; 
 
 TestElement.created（）：super.created（）{
 ds = new VerySimpleTest（）.. name ='Peter'; 
} 
} 
  

ds.dart

  class VerySimpleTest extends Observable {
 @observable String name =''; 
 @observable String get fullname => 'test：$ name'; 
 VerySimpleTest（）：super（）; 
} 
  

解决方案

一个值已改变getter依赖。

 字符串集name（String val）{
 name = notifyPropertyChange（#fullname，name，val）; 
} 
  

或者这也应该工作

  @ComputedProperty（'Test：$ name'）String get fullname => 'test：$ name'; 
  

查看 http://japhr.blogspot.co.at/2014/08/the-polymerdart-computedproperty.html 了解更多详情。

I am trying to understand how observable getters work when they use other class instance properties:

When I bind the implicit getter/setter pair 'name' it updates in the input and in the div and everything is synced nicely.

However the explicit getter 'fullname' is not updating in the HTML. Is there a way to make that work (basically the 'fullname' in the element binding should update as well)?? Maybe I am missing a setter, but then again setter does not make sense here...

Very simple example to demonstrate:

test-element.html

<link rel="import" href="../../packages/polymer/polymer.html">
<polymer-element name="test-element">
  <template>
    <input value="{{ds.name}}">
    <div>{{ds.name}}</div>
    <div>{{ds.fullname}}</div>
  </template>
  <script type="application/dart" src="test1.dart"></script>
</polymer-element>

test-element.dart

import 'package:polymer/polymer.dart';
import 'package:popoli/sysmaster-settings.dart';

@CustomTag('test-element')
class TestElement extends PolymerElement {
  @observable VerySimpleTest ds;

  TestElement.created() : super.created() {
    ds = new VerySimpleTest()..name = 'Peter';
  }
}

ds.dart

class VerySimpleTest extends Observable {
  @observable String name = '';
  @observable String get fullname => 'Test: $name';
  VerySimpleTest() : super();
}

解决方案

You need to notify Polymer that a value has changed the getter depends on.

String set name(String val) {
  name = notifyPropertyChange(#fullname, name, val);
}

or this should work too

@ComputedProperty('Test: $name') String get fullname => 'Test: $name';

See http://japhr.blogspot.co.at/2014/08/the-polymerdart-computedproperty.html for more details.

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