Angular 7 给出 this.interceptor is undefined 错误

Question

我试图在 angular7 中实现一个 HTTP 拦截器，但它给出了 "this.interceptor is undefined" 错误。这是什么原因？

auth.service.ts - 我在哪里进行 http 调用

@Injectable()
export class AuthService{

    constructor(private httpClient: HttpClient){}

    login(userName, password){
        return this.httpClient.post('/authenticate', {"username" : userName, "password" : password});
    }
}

app.module.ts

@NgModule({
  declarations: [
    AppComponent,
    LoginComponent,
  ],
  imports: [
    BrowserModule,
    AppRoutingModule,
    FormsModule,
    HttpClientModule,
  ],
  providers: [AuthService, fakeBackendProvider],
  bootstrap: [AppComponent]
})

export class AppModule { }

拦截器

import { HTTP_INTERCEPTORS, HttpInterceptor,  HttpHandler, HttpEvent} from '@angular/common/http';

class FakeBackendInterceptor implements HttpInterceptor {

   intercept(request: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
      const { url, method, headers, body } = request;
      return next.handle(request);
   }

}

export const fakeBackendProvider = {
   provide: HTTP_INTERCEPTORS,
   useFactory: FakeBackendInterceptor,
   multi: true
}

这是我得到的错误，

Answer 1

需要在模块中以不同方式提供拦截器：

  providers: [
    {
      provide: HTTP_INTERCEPTORS,
      useClass: FakeBackendProvider,
      multi: true
    }
  ]

确保从 @angular/common/http 导入 HTTP_INTERCEPTORS。有关拦截器以及如何提供拦截器的更多信息，请参阅 docs.

Angular 7 给出 this.interceptor is undefined 错误

Angular 7 gives this.interceptor is undefined error

typescript

angular-http-interceptors

angular