javascript - Angular 从子组件更新 UI 将值反射(reflect)到父组件

Question

我正在 Angular 5 中使用 *IF-else 语句。如果授权值为 true，则模板 2 应该呈现，如果模板 1 不应该呈现的话。这是代码

<div *ngIf="authorized; then picUrl else login"></div>

                <ng-template #login>
                    <button mat-raised-button color="accent" class="mdl-cell mdl-cell--12-col mdl-color-text--white" style="background: #033342" (click)="openDialog()">Login</button>
                </ng-template>
                <ng-template #picUrl>
                    <img src="{{_loginVM.profilePic}}" class="img-thumbnail" alt="profile pic">
                </ng-template>

调用社交组件

<social></social>

App.component.ts

export class AppComponent {
    public authorized: boolean = false;
}

社交组件.ts

import { AppComponent} from '../app/app.component'

    export class SocialComponent {
        private _appComponent: AppComponent;
        constructor(private socialAuthService: AuthService, appComponent: AppComponent,
            public dialogRef: MatDialogRef<SignInSignUpDialogHomeComponent>) {
            this._appComponent = appComponent;
        }
     public socialSignIn(socialPlatform: string) {
            let socialPlatformProvider: any;
            if (socialPlatform == "facebook") {
                socialPlatformProvider = FacebookLoginProvider.PROVIDER_ID;
            } else if (socialPlatform == "google") {
                socialPlatformProvider = GoogleLoginProvider.PROVIDER_ID;
            }

            this.socialAuthService.signIn(socialPlatformProvider).then(
                (userData) => {
                    if (userData != null) {
                        this._appComponent.authorized = true;
                        this._appComponent._loginVM.profilePic = userData.image;
                        this.dialogRef.close();
                    }
                }
            );
        }

成功登录后该值更新为this._appComponent.authorized = true; 。该值不会反射(reflect)到 UI/UX。

我从这里找到了一些引用资料 https://angularfirebase.com/lessons/sharing-data-between-angular-components-four-methods/

我尝试过 BehaviorSubject<boolean> 。但不知道如何订阅UI数据绑定(bind)。难道，这就是我，必须要做的事？我不能直接对组件变量执行操作吗？

Answer 1

.html

<div *ngIf="authorized; then picUrl else login"></div>

组件.ts

ngOnInit() {
this.authorized= this.authService.isLoggedIn;
}

服务.ts

get isLoggedIn(): boolean {
    return this.currentUser != null; //you can decide to return true or false
 }
get currentuser(): user{
  let user = localstorage.getitem('details')
return user;
}