如何使用app-route在聚合物3中实现路由 [英] How to implement routing in polymer 3 using app-route

问题描述

我一直坚持在聚合物3中实现路由.我遵循了 app-route 文档中提供的基本指南.但是在加载网页时，我看不到任何组件被加载.我签入了shadow DOM，没有看到任何DOM呈现出来.不知道我在想什么.这是代码.

I was stuck with implementing routing in polymer 3. I followed the basic guide provided on app-route documentation. But on loading the web page., I don't see any component getting loaded. I checked in shadow DOM and don't see any DOM getting rendered. Not sure what I`m missing. Here is the code.

static get properties() {
      return {
      page:{
        type: String,
        reflectToAttribute: true,
        observer: '_pageChanged'
      }
      };
    }
    _pageChanged(currentPage, oldPage){
    	  console.log('CURRENT - ', currentPage);
    	  console.log('OLD - ', oldPage);
    	  switch(currentPage){
    		  case 'home':
    			import('./home-comp.js').then()
    			break;
    		case 'about':
    			import('./about-comp.js').then()
    			break;
    		case 'contact':
    			import('./contact-comp.js').then()
    			break;
    		default:
    			this.page = 'home';
    	  }
      }

<app-route
          route="{{route}}"
          pattern="/:page"
          data="{{routeData}}"
          tail="{{subroute}}">
</app-route>

<home-comp name="home"></home-comp>
<about-comp name="about"></about-comp>
<contact-comp name="contact"></contact-comp>

我看不到许多有关Polymer 3的文档可用于检查问题.在查看Polymer默认的示例Web应用程序shop.之后，我遇到了一些适当的解决方案.我想与社区分享给任何需要帮助的人.

I don`t see lot of documentation on Polymer 3 available for checking on issues. After going through Polymer default sample web application, shop., I came across some proper solution. I would like to share it with community for any any one in need of help for same.

推荐答案

您需要

应用程序路由:用于实施路由

铁页面:基本上是页面切换器，可按需加载所需组件

Iron pages: Basically page switcher to load required component on demand

在应用路由中，

/* observer: Its a simple observer (basically a watch which holds current value & old value) that triggers whenever data changed in page property. We read the observer and calls a function to grab its earlier */

static get properties() {
  return {
  page:{
    type: String,
    reflectToAttribute: true,
    observer: '_pageChanged'
  }
  };
}
_pageChanged(currentPage, oldPage){
	  console.log('CURRENT - ', currentPage);
	  console.log('OLD - ', oldPage);
	  switch(currentPage){
		  case 'home':
			import('./home-comp.js').then()
			break;
		case 'about':
			import('./about-comp.js').then()
			break;
		case 'contact':
			import('./contact-comp.js').then()
			break;
		default:
			this.page = 'home';
	  }
  }

<!-- pattern: reads the href property., hence set the page (pattern="/:page") property in static get property to read its data -->

<app-route route="{{route}}" pattern="/:page" data="{{routeData}}" tail="{{subroute}}"></app-route>
	<ul>
	    <li>
		    <a href="/home">Home</a>
	    </li>
	    <li> 
          <a href="/about">About</a> 
      </li>
	    <li> 
          <a href="/contact">Contact</a> 
      </li>
	</ul>

但是对于第一次加载.，页面属性不保存任何值并抛出undefined.

But for first time loading., page property doe not hold any value and throws undefined.

因此，我们可以使用complex observer观察这种变化

Hence we can use complex observer to observe such changes

static get observers(){
	return ['_routerChanged(routeData.page)'];
}
_routerChanged(page){
	console.log('CHANGED PAGE - ', page);
	this.page = page || 'home';
}

更改的路线数据不会加载组件，除非我们具有iron-pages.它基本上是按需提供的组件切换器/加载器.将所有组件包装在<iron-pages>下的main-app

Changed route data does not load the components unless we have iron-pages. Its basically a component switcher/loader on demand. Wrap all component in main-app under <iron-pages>

<!-- selected: Data binding helps to get changed page value -->
<!-- attr-for-selected: It reads value of name attr defined in each component & matches with selected value and triggers page switch -->

<!-- fallback-selection: for 404., page/component not found handling -->

<iron-pages selected="[[page]]" attr-for-selected="name" selected-attribute="visible" fallback-selection="404">
		<home-comp name="home"></home-comp>
		<about-comp name="about"></about-comp>
		<contact-comp name="contact"></contact-comp>
</iron-pages>

此处是使用app-route在聚合物3中路由实施的完整指南.希望这有助于单击此处

Here is the complete guide for routing implementation in polymer 3 using app-route. Hope this helps click here

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