实现CanDeactivate保护时出错

Question

我目前正在尝试为我的CanDeactivate应用程序实现一个HTTP，该应用程序已经有了HTTP来解析身份验证。但是添加CanDeactivate保护是抛出错误，如下所述。

我已经在CanDeactivate的提供者数组中注册了实现AppModule接口的类。我已经在路由的CanDeactivate属性中注册了实现canDeactivate接口的类。

类实现CanDeactivate接口：

export interface CanComponentDeactivate {
  canComponentDeactivate(): boolean;
}

@Injectable({providedIn: 'root'})
export class AppRegisterDeactivateGuard implements CanDeactivate<AppRegisterComponent> {
  canDeactivate(
    component: AppRegisterComponent,
    currentRoute: ActivatedRouteSnapshot,
    currentState: RouterStateSnapshot
  ): Observable<boolean>|Promise<boolean>|boolean {
    return component.isDeactivated;
  }
}

应用停用保护的组件：

@Component({
  selector: 'app-app-register',
  templateUrl: './app-register.component.html',
  styleUrls: ['./app-register.component.css']
})
export class AppRegisterComponent implements OnInit, CanComponentDeactivate {
  isDeactivated = false;
  @ViewChild('registrationForm') registForm: NgForm;
.
.
canComponentDeactivate() {
    if (this.registForm.dirty) {
      this.isDeactivated = confirm('You have modified changes in the form. \nDo you still want to navigate away ? ');
    }
    return this.isDeactivated;
  }
}

该端点的路由定义：

...
{ path: 'register', component: AppRegisterComponent, canDeactivate: ['AppRegisterDeactivateGuard'] },

模块中的提供者数组：

 providers: [{
    provide: HTTP_INTERCEPTORS,
    useClass: AppAuthInterceptService,
    multi: true
  }, AppRegisterDeactivateGuard],
  bootstrap: [AppComponent]

错误

  StaticInjectorError(Platform: core)[AppRegisterDeactivateGuard]: 
    NullInjectorError: No provider for AppRegisterDeactivateGuard!
Error: StaticInjectorError(AppModule)[AppRegisterDeactivateGuard]: 
  StaticInjectorError(Platform: core)[AppRegisterDeactivateGuard]: 
    NullInjectorError: No provider for AppRegisterDeactivateGuard!
    at NullInjector.push../node_modules/@angular/core/fesm5/core.js.NullInjector.get (core.js:8896)
    at resolveToken (core.js:9141)
    at tryResolveToken (core.js:9085)
    at StaticInjector.push../node_modules/@angular/core/fesm5/core.js.StaticInjector.get (core.js:8982)
    at resolveToken (core.js:9141)
    at tryResolveToken (core.js:9085)
    at StaticInjector.push../node_modules/@angular/core/fesm5/core.js.StaticInjector.get (core.js:8982)
    at resolveNgModuleDep (core.js:21218)
    at NgModuleRef_.push../node_modules/@angular/core/fesm5/core.js.NgModuleRef_.get (core.js:21907)
    at getToken (router.js:2865)
    at resolvePromise (zone.js:831)
    at resolvePromise (zone.js:788)
    at zone.js:892
    at ZoneDelegate.push../node_modules/zone.js/dist/zone.js.ZoneDelegate.invokeTask (zone.js:423)
    at Object.onInvokeTask (core.js:17290)
    at ZoneDelegate.push../node_modules/zone.js/dist/zone.js.ZoneDelegate.invokeTask (zone.js:422)
    at Zone.push../node_modules/zone.js/dist/zone.js.Zone.runTask (zone.js:195)
    at drainMicroTaskQueue (zone.js:601)
    at ZoneTask.push../node_modules/zone.js/dist/zone.js.ZoneTask.invokeTask [as invoke] (zone.js:502)
    at invokeTask (zone.js:1744)

Answer 1

改变您的路线：

{ path: 'register', component: AppRegisterComponent, canDeactivate: [AppRegisterDeactivateGuard] }

将提供程序更改为：

[{
    provide: HTTP_INTERCEPTORS,
    useClass: AppAuthInterceptService,
    multi: true
  }]

较长的答覆：

AppRegisterDeactivateGuard既拥有{providedIn: 'root'}又将其声明为模块中的提供程序是不必要的。请参阅角提供程序文档。

这里的问题是与路由和提供者的结合。

现在，您的路由正在通过字符串名称查找令牌，但是它可以通过类名获得。

使用@Injectable({providedIn: 'root'}) --如何使用它--它使用类名作为令牌，并且它可以作为AppRegisterDeactivateGuard使用。

在您的提供者中使用AppRegisterDeactivateGuard (如何使用它)也将使它可以作为AppRegisterDeactivateGuard使用。

我不建议这样做，但如果您希望或需要通过字符串名称引用它，您可以将其放在提供程序中，如下所示：

{ provide: 'AppRegisterDeactivateGuard', useClass: AppRegisterDeactivateGuard }

Answer 2

您需要在泛型中传递接口：

export class AppRegisterDeactivateGuard implements CanDeactivate<CanComponentDeactivate > {

然后实现canDeactivate方法。