如何在不刷新整个页面的情况下更新组件-角度

BehaviorSubject 用于在整个应用程序的不同组件之间进行通信。您可以定义一个包含 您可以订阅并发出更改。

定义数据共享服务

import { Injectable } from '@angular/core';
import { BehaviorSubject } from 'rxjs';

@Injectable()
export class DataSharingService {
    public isUserLoggedIn: BehaviorSubject<boolean> = new BehaviorSubject<boolean>(false);
}

DataSharingService 在你的 AppModule 提供者条目。

接下来,导入 数据共享服务 在你的 <app-header> <应用标题> 订阅对的更改 isUserLoggedIn

import { DataSharingService } from './data-sharing.service';

export class AppHeaderComponent { 
    // Define a variable to use for showing/hiding the Login button
    isUserLoggedIn: boolean;

    constructor(private dataSharingService: DataSharingService) {

        // Subscribe here, this will automatically update 
        // "isUserLoggedIn" whenever a change to the subject is made.
        this.dataSharingService.isUserLoggedIn.subscribe( value => {
            this.isUserLoggedIn = value;
        });
    }
}

在你的 <应用标题> html模板,您需要添加 *ngIf

<button *ngIf="!isUserLoggedIn">Login</button> 
<button *ngIf="isUserLoggedIn">Sign Out</button>

最后,您只需要在用户登录后发出事件,例如:

someMethodThatPerformsUserLogin() {
    // Some code 
    // .....
    // After the user has logged in, emit the behavior subject changes.
    this.dataSharingService.isUserLoggedIn.next(true);
}

为了定期刷新组件,我发现这是最好的方法。

ngOnInit(): void {
  setTimeout(() => { this.ngOnInit() }, 1000 * 10)
}
//10 is the number of seconds

@Injectable() 类,该类保存要在标头中显示的数据。其他组件也可以访问该类并更改该数据,从而有效地更改标头。

另一种选择是设置 @Input() 变量和 @Output()

@Injectable()
export class HeaderService {
    private _data;
    set data(value) {
        this._data = value;
    }
    get data() {
        return this._data;
    }
}

在其他组件中:

constructor(private headerService: HeaderService) {}

// Somewhere
this.headerService.data = 'abc';

在标题组件中:

let headerData;

constructor(private headerService: HeaderService) {
    this.headerData = this.headerService.data;
}

实际上我还没有试过这个。如果get/set不起作用,可以将其更改为使用Subject();

// Simple Subject() example:
let subject = new Subject();
this.subject.subscribe(response => {
  console.log(response); // Logs 'hello'
});
this.subject.next('hello');

Angular在检测到变量变化时将自动更新组件。

header.component.ts 或通过 @Input 变量

主要的html

<app-header [header-data]="headerData"></app-header>

public headerData:int = 0;

ngOnInit(){
    setInterval(()=>{this.headerData++;}, 250);
}

标题。html

<p>{{data}}</p>

@Input('header-data') data;

在上述示例中,报头将每隔250ms接收一次新数据,从而更新组件。

有关Angular的生命周期挂钩的更多信息,请参阅: https://angular.io/guide/lifecycle-hooks

更新组件的步骤

 @Injectable()
    export class LoginService{
    private isUserLoggedIn: boolean = false;

    public setLoggedInUser(flag) { // you need set header flag true false from other components on basis of your requirements, header component will be visible as per this flag then
    this.isUserLoggedIn= flag;
    }


public getUserLoggedIn(): boolean {
return this.isUserLoggedIn;
}

Login Component ts
            Login Component{
             constructor(public service: LoginService){}

public login(){
service.setLoggedInUser(true);
}
            }
Inside Header component

 Header Component ts
        HeaderComponent {
         constructor(public service: LoginService){}

         public getUserLoggedIn(): boolean { return this.service.getUserLoggedIn()}
        }

template of header component: Check for user sign in here

<button *ngIf="getUserLoggedIn()">Sign Out</button>
<button *ngIf="!getUserLoggedIn()">Sign In</button>

App Component ts
AppComponent {
 public showHeader: boolean = true;
}
App Component html
<div *ngIf='showHeader'> // you show hide on basis of this ngIf and header component always get visible with it's lifecycle hook ngOnInit() called all the time when it get visible
<app-header></app-header>
</div>
<router-outlet></router-outlet>
<app-footer></app-footer>

您也可以使用服务

@Injectable()
export class AppService {
private showHeader: boolean = false;

public setHeader(flag) { // you need set header flag true false from other components on basis of your requirements, header component will be visible as per this flag then
this.showHeader = flag;
}

public getHeader(): boolean {
return this.showHeader;
}
}

App Component.ts
    AppComponent {
     constructor(public service: AppService){}
    }

App Component.html
    <div *ngIf='service.showHeader'> // you show hide on basis of this ngIf and header component always get visible with it's lifecycle hook ngOnInit() called all the time when it get visible
    <app-header></app-header>
    </div>
    <router-outlet></router-outlet>
    <app-footer></app-footer>

您只需要通知Angular使用 ChangeDetectorRef . 因此,在标题组件中:

constructor(private cd: ChangeDetectorRef) {}

loggedUserEvent(user: User): void {
  this.username = user.username; 
  this.enableDisconnectButton();

  //... Add more logic to it

  this.cd.detectChanges();
}