Question

是Angular2的新手，但我已经制作了30多个组件和服务，并使用了Input，Output，ChangeDetectorRef，Pipes。所以现在非常了解Angular2。我的app.component.ts看起来像这样

import { Component } from '@angular/core';
@Component({
    selector: 'soc',
    template: `
        <header-block></header-block>
        <router-outlet></router-outlet>
    `,
})
export class AppComponent { }

因为我需要在每个页面中使用我的标题块所以我将它添加到路由器块之外，所以我不必在任何地方添加它。现在我遇到的问题是在路由器插座内部执行操作后更改标头块中的变量值。

例如，我有一个菜单，只有在用户登录后才能看到。

{{ user_is_logged }}
<ul class="nav navbar-nav navbar-right" *ngIf="user_is_logged == '1'">
    <li><a href="#" (click)="logout($event)">Logout</a></li>
</ul>

user_is_logged 是一个变量，其值来自 header.block.component.ts

中的localStorage

user_is_logged:string = localStorage.getItem("logged");

当用户未登录时，即 home.component.ts （写入登录逻辑）未定义user_is_logged，我要求用户登录并在成功登录后更新值 user_is_logged 变量，还会更新变量的localStorage值，然后使用ChangeDetectionRef（cdr）触发检测更改，然后路由到用户配置文件

this.user_is_logged = "1";
localStorage.setItem('logged', '1');
this.cdr.detectChanges();
this.router.navigate(['u/'+user_id']); //user_id is from login response from server

问题是当我在成功登录后到达用户配置文件时，{{user_is_logged}}的值永远不会更新，即使在使用变量本身或使用localStorage中的值甚至调用检测时也是如此。

是否可以这样做或者我必须分别为每个页面添加header-block？如果我错过了什么，请询问更多信息。

编辑 ============＆gt;

因此，在浏览了Subject，BehaviourSubject，AsyncSubject，ReplaySubject，Observables以及我不能让它工作的时候。这是我写的最后一个代码：

home.page.component.ts （登录发生且必须发出事件）

import { HomeService } from '../services/home.service';
// No observable or subject imported here.

login() {
    // Sending status 1 to HomeService
    this.HomeService.changeStatus("1");
}

home.service.ts （由两个组件导入）

import { BehaviorSubject } from 'rxjs/BehaviorSubject';
// I imported Subject, BehaviourSubject, Observables but cant get it to work

export class HomeService {

    // This looked more reliable than Subject so used this; init with value "0"
    public subjectStream = new BehaviorSubject<string>('0');


    constructor(
    ){
        this.subjectStream.subscribe(value => {
            // Successfully logs value "1" sent by changeStatus below
            console.log(value);
        });
    }


    changeStatus(value: any){

        // Gives value "1" when called by home.page.component.ts
        console.log(value);

        // Looks correct because it successfully sent value to construct
        this.subjectStream.next(value);

    }

}

header.block.component.ts

import { HomeService } from '../services/home.service';
// No observable or subject imported here also.


constructor(
){
    this.HomeService.subjectStream.subscribe(value => {
        // Logs value "0" at beginning but never logs value "1"
        console.log(value);
    });
}

我的日志

// logged by constructor when imported by header.block.component
home.service.ts:31                  0

// logged by constructor of header.block.component itself
header.block.component.ts:25        0

// logged by constructor when imported by home.page.component (I think)
home.service.ts:31                  0

// ===================
// Login called here
// ===================

// logged by changeStatus after login after called by home.component
home.service.ts:36                  1 

// logged by constructor after getting event from changeStatus
home.service.ts:31                  1

header.block.component.ts中缺少什么？由于该值在home.service.ts中成功更新，但从未进入标题。

Answer 1

被要求发布这个，这是一个简单的活动/主题服务，让你开始。我使用“notifier / notes / note”只是因为命名法不会与“事件”和其他框架-api机制混淆。

// Constant of named "notes" analogous to named events. 
// I always found it easier to have one event type with a "name",
// rather than creating a specific typed event for every action. 
const Notes = {
    HEADER_BUTTON_CLICKED : 'header_button_clicked'
};

// Any component that wants to send data creates a new "Note" to send.
// Just makes sure you know what all callbacks are getting.
class Note {
    constructor ( name, data ) {
        this.name = name; // Should be from your Notes constant.
        this.data = data; // Can be anything at all.
    }
}

// You inject this service into any component that needs it. 
class NotifierService {

    constructor() {

        let Rx = require ( 'rx' );
        // We'll use Subject here. 
        this.subject = new Rx.Subject ( );
    }

    // You only subscribe if you want to hear notes. 
    subscribe ( callback ) {
        // Subscribing component feeds in a callback.
        // The return of this can be used to unsubscribe as well.
        return this.subject.subscribe ( b => callback ( b ) );
    }

    // Any component with access to this service can just create a note
    // and send it to all subscribers to this service. 
    sendNote ( note ) {
       // Component uses the service to emit a "note" with a 
       // named event and a payload. All subscribers hear it in the
       // callbacks they subscribed with, and can filter on the name
       // in the "note" to make sure it's the event they care about. 
       // This is pretty naive but should give the idea.
       this.subject.onNext ( note );
    }
}
export { NotifierService } // Service to inject
export { Note } // A useful type to send out to subscribers 
export { Notes } // Constant of event/note names.

典型用法：

import { NotifierService, Notes, Note } from './notifier.service';
... // inject in your constructor either TS or ES6 style...

// I want to hear notes
this.noteSvc.subscribe ( b => this.myCallback ( b ) );

// I want to send a note
this.noteSvc.sendNote ( new Note ( Notes.HEADER_BUTTON_CLICKED, { btnName : 'Home' } );

   // In the callback 
   myCallback ( note ) {
     if ( note.name === Notes.HEADER_BUTTON_CLICKED ) {
        console.log ( note.data ); // whatever the payload is
     }
   }

Answer 2

如果您在首页和标题中提供HomeService，则会获得HomeService的2个实例。如果要共享服务，则只在父组件上提供一次。如果您想与整个应用程序共享一个实例，请仅在@NgModule() AppModule

时提供该实例

Angular2 - 将路由器出口外的数据传输到另一个组件

2 个答案: