【发布时间】：2014-01-12 01:25:54
【问题描述】：
当模型类在导入的打包库中定义时，在聚合物元素中使用模型的正确方法是什么？
我相信我做对了（基于更多文章，例如 How to subscribe to change of an observable field）。
它可以在 DARTIUM 中运行，但是当它构建到 JS 时就不行了。我无法弄清楚那里发生了什么，请参阅日志。字段中的侦听器和值表现得很奇怪。
关键因素：我的模型类由于某些原因被打包在共享库中，必须使用我的输入元素
我错过了什么？还是 dart2js 有 bug？
文件和日志
testlib.dart（只是打包库中的模型，不是聚合物应用程序的一部分）：
library testlib;
import 'package:observe/observe.dart';
class MyModel extends Object with Observable{
@observable String foo;
String toString(){
return "MyModel[foo:$foo]";
}
}
在聚合物应用程序中，我们有：
all_elements.dart（模型是使用包导入的：...）
library test;
import 'package:polymer/polymer.dart';
import 'package:testlib/testlib.dart'; //!!!! note this is important, I need shared model
@CustomTag('my-input')
class MyInput extends PolymerElement {
@published String value;
valueChanged(oldValue){
print('text changed from "$oldValue" to "$value"');
}
MyInput.created() : super.created();
}
@CustomTag('my-form')
class MyForm extends PolymerElement {
@observable MyModel model = new MyModel();
modelChanged(oldValue){
print('text changed from "$oldValue" to "$model"');
}
MyForm.created() : super.created();
void ready(){
model.changes.listen((changes){
print('model properties changed $changes');
});
}
}
和all_elements.html
<polymer-element name="my-input">
<template>
<p>My Input</p>
<input type="text" value="{{value}}"/>
</template>
</polymer-element>
<polymer-element name="my-form">
<template>
<my-input value="{{model.foo}}"></my-input>
</template>
</polymer-element>
<script type="application/dart" src="all_elements.dart"></script>
和应用入口点：testapp.html
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Test app</title>
<link rel="import" href="all_elements.html">
<script type="application/dart">export 'package:polymer/init.dart';</script>
<script src="packages/browser/dart.js"></script>
</head>
<body>
<my-form></my-form>
</body>
</html>
日志：
在构建到 JS 之前一切正常。当尝试写单词“hello”来输入时，我得到：
DARTIUM - 好的
text changed from "null" to "h"
model properties changed [#<PropertyChangeRecord Symbol("foo") from: null to: h>]
text changed from "h" to "he"
model properties changed [#<PropertyChangeRecord Symbol("foo") from: h to: he>]
text changed from "he" to "hel"
model properties changed [#<PropertyChangeRecord Symbol("foo") from: he to: hel>]
text changed from "hel" to "hell"
model properties changed [#<PropertyChangeRecord Symbol("foo") from: hel to: hell>]
text changed from "hell" to "hello"
model properties changed [#<PropertyChangeRecord Symbol("foo") from: hell to: hello>]
JavaScript - 问题（输入“hello” - 获取“hel”，输入“mystery” - 获取“mytr”）
text changed from "null" to "h"
model properties changed [#<PropertyChangeRecord Symbol("foo") from: null to: h>]
text changed from "h" to "he"
text changed from "he" to "h"
model properties changed [#<PropertyChangeRecord Symbol("foo") from: h to: he>]
text changed from "h" to "hl"
text changed from "hl" to "he"
model properties changed [#<PropertyChangeRecord Symbol("foo") from: he to: hl>]
text changed from "he" to "hel"
text changed from "hel" to "hl"
model properties changed [#<PropertyChangeRecord Symbol("foo") from: hl to: hel>]
text changed from "hl" to "hlo"
text changed from "hlo" to "hel"
【问题讨论】：
标签： dart dart-polymer dart-pub