我想创建一个控件,将数据转换为我需要的东西。
目前,我使用全局变量来解决这个问题。代码看起来像这样:
(小写功能只是为了以简单的方式进行演示。通常,我想将其用于对象数组,例如获取某些名称和ID的不同值)
<dom-module id="my-tolower">
<script>
"use strict";
Polymer({
is: 'my-tolower',
properties: {
input: {
type: String,
value: "",
},
output:{
type: String,
value: "",
notify: true,
}
},
observers:[
"_inputChanged(input)",
],
_inputChanged: function(newInput, oldInput){
this.set("output", newInput.toLowerCase());
}
});
</script>
</dom-module>
用法:
<my-tolower input="[[output.name]]" output="{{lower}}">[[lower]]</my-tolower>
如果我仅使用变量
lower
一次,则此解决方案效果很好。在<dom-repeat>
内部,出现问题。如何轻松创建仅在
my-tolower
内部可用的自定义变量?与Polymer的dom-repeat
完全一样吗?我看了Polymer's
<dom-repeat>
sources处的代码,但我不知道它是如何工作的。在自定义元素中甚至可能吗?我需要创建自定义模板吗?为了更好地解释我的问题,我添加了一个更大的Example来详细解释我的问题。
HTMLImports.whenReady(() => {
Polymer({
is: 'my-app',
ready: function(){
//In my real Problem this value comes from a websocket...
this.devices = [{
name: "PC 1",
components: [
{
name: "HDD1",
processors: [
{
type: "Processor1",
usage: "Dont Know 1"
},
{ type: "Processor1", usage: "DontKnow2"},
{ type: "Processor2", usage: "DontKnow3"}
]
},
{
name: "Another Piece Of Hardware",
processors: [
{
type: "Processor4",
usage: "Dont Know 1"
},
{ type: "Processor3", usage: "DontKnow2"},
{ type: "Processor4", usage: "DontKnow3"}
]
}
]
},
{
name: "PC 2",
components: [
{
name: "My third piece of hardware",
processors: [
{
type: "Processor1",
usage: "Dont Know 1"
},
{ type: "Processor2", usage: "DontKnow2"},
{ type: "Processor3", usage: "DontKnow3"}
]
}
]
}];
//this.devices must not be changed!
}
});
Polymer({
is: 'my-distinct',
properties: {
inputs: {
type: String
},
outputs:{
computed: '_getDistincts(inputs, path)',
notify: true
},
path: {
type: String,
value: ""
}
},
_getDistincts(inputs, path){
let result = [];
for(let key in inputs){
if(inputs.hasOwnProperty(key)){
let x = inputs[key];
if(path && path != ""){
x = x[path];
}
if(result.indexOf(x) < 0){
result.push(x);
}
else{
//Already Exists
}
}
}
return result;
}
});
});
<head>
<base href="https://polygit.org/polymer+1.8.1/components/">
<script src="webcomponentsjs/webcomponents-lite.js"></script>
<link rel="import" href="polymer/polymer.html">
</head>
<body>
<my-app></my-app>
As you can see, there is always "Processor1", "Processor2" and "Pocessor3" available although this is only the result of the last computers component. You can see the right result (but with duplicates) if you use the comment I made instead.
<dom-module id="my-app">
<template>
<ul>
<template is="dom-repeat" items="[[devices]]" as="device">
<li>[[device.name]]
<ul>
<template is="dom-repeat" items="[[device.components]]" as="component">
<li>[[component.name]]
<ul>
<!-- This is my code with using distinct -->
<my-distinct inputs="[[component.processors]]"
outputs="{{distinctProcessorNames}}"
path="type">
<template is="dom-repeat" items="[[distinctProcessorNames]]" as="processorName">
<li>[[processorName]]
<!-- Here I could iterate over all processors (filtered) and list their usages-->
</li>
</template>
</my-distinct>
<!-- This is my code without using distinct. -->
<!--template is="dom-repeat" items="[[component.processors]]" as="processor">
<li>[[processor.type]]
<ul>
<li>Used for [[processor.usage]]</li>
</ul>
</li>
</template-->
</ul>
</li>
</template>
</ul>
</li>
</template>
</ul>
</template>
</dom-module>
</body>
Demo
最佳答案
您正在使用2个不同的Polymer自定义元素<my-app>
和<my-distinct>
。
因此,您应该使用正确的<dom-module>
语句声明第二个:
<dom-module id="my-distinct">
<template>
<template is="dom-repeat" items="[[outputs]]" as="processorName">
<li>[[processorName]]
</template>
</template>
</dom-module>
然后将您计算的属性(基于属性值)
outputs
用作items
的<template is="dom-repeat">
值。下面的演示:
HTMLImports.whenReady(() => {
Polymer({
is: 'my-app',
ready: function(){
//In my real Problem this value comes from a websocket...
this.devices = [{
name: "PC 1",
components: [
{
name: "HDD1",
processors: [
{
type: "Processor1",
usage: "Dont Know 1"
},
{ type: "Processor1", usage: "DontKnow2"},
{ type: "Processor2", usage: "DontKnow3"}
]
},
{
name: "Another Piece Of Hardware",
processors: [
{
type: "Processor4",
usage: "Dont Know 1"
},
{ type: "Processor3", usage: "DontKnow2"},
{ type: "Processor4", usage: "DontKnow3"}
]
}
]
},
{
name: "PC 2",
components: [
{
name: "My third piece of hardware",
processors: [
{
type: "Processor1",
usage: "Dont Know 1"
},
{ type: "Processor2", usage: "DontKnow2"},
{ type: "Processor3", usage: "DontKnow3"}
]
}
]
}];
//this.devices must not be changed!
}
});
Polymer({
is: 'my-distinct',
properties: {
inputs: {
type: String
},
outputs:{
computed: '_getDistincts(inputs, path)', notify: true
},
path: {
type: String,
value: ""
}
},
_getDistincts(inputs, path){
let result = [];
for(let key in inputs){
if(inputs.hasOwnProperty(key)){
let x = inputs[key];
if(path && path != ""){
x = x[path];
}
if(result.indexOf(x) < 0){
result.push(x);
}
}
}
//console.log( result )
return result;
}
});
});
<head>
<base href="https://polygit.org/polymer+1.8.1/components/">
<script src="webcomponentsjs/webcomponents-lite.js"></script>
<link rel="import" href="polymer/polymer.html">
</head>
<body>
<my-app></my-app>
<dom-module id="my-app">
<template>
<ul>
<template is="dom-repeat" items="[[devices]]" as="device">
<li>[[device.name]]
<ul>
<template is="dom-repeat" items="[[device.components]]" as="component">
<li>[[component.name]]
<ul>
<my-distinct inputs="[[component.processors]]" path="type">
</my-distinct>
</ul>
</li>
</template>
</ul>
</li>
</template>
</ul>
</template>
</dom-module>
<dom-module id="my-distinct">
<template>
<template is="dom-repeat" items="[[outputs]]" as="processorName">
<li>[[processorName]]
</template>
</template>
</dom-module>
</body>