Angular2 模块没有导出成员

Question

For a website with authentication in Angular2, I want to use a component of the authentication submodule in the main app component. However, I keep getting the following error:

app/app.component.ts(3,10): error TS2305: Module '"<dir>/app/auth/auth.module"' has no exported member 'SigninComponent'.

even after exporting SigninComponent.

The project folder structure is as shown below:

app/auth/auth.module.ts:

import { NgModule }       from '@angular/core';
import { CommonModule }   from '@angular/common';
import { FormsModule }    from '@angular/forms';

import { RegisterComponent }    from './components/register.component';
import { SigninComponent }    from './components/signin.component';
import { HomeComponent }    from './components/home.component';

import { AuthService } from './services/auth.service';
import { AuthHttp } from './services/auth-http';

@NgModule({
  imports: [
      CommonModule,
      FormsModule
  ],
  declarations: [
      RegisterComponent,
      SigninComponent,
      HomeComponent
  ],
  providers: [
      AuthService,
      AuthHttp
  ],
  exports: [
      RegisterComponent,
      SigninComponent,
      HomeComponent
  ]
})
export class AuthModule {}

app/auth/components/signin.component.ts:

import { Component } from '@angular/core';
import { Router } from '@angular/router';
import { AuthService } from '../services/auth.service';

@Component({
    selector: 'signin',
    templateUrl: 'app/auth/signin.html'
})
export class SigninComponent {
    ...
}

app/app.component.ts:

import { Component, OnInit } from '@angular/core';
import { Router, RouterOutlet } from '@angular/router';
import { SigninComponent, RegisterComponent } from './auth/auth.module';
import { AuthHttp } from './auth/services/auth-http';
import { AuthService } from './auth/services/auth.service';

@Component({
    selector: 'myapp',
    templateUrl: 'app/app.html'
})

export class AppComponent implements OnInit {
    ...
}

app/app.module.ts:

import { NgModule }      from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { FormsModule }   from '@angular/forms';
import { HttpModule }    from '@angular/http';
import { RouterModule } from '@angular/router';
import { AppRoutingModule } from './app-routing.module';
import { AuthModule } from './auth/auth.module';

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

import { AuthService } from './auth/services/auth.service';
import { AuthHttp } from './auth/services/auth-http';

@NgModule({
  declarations: [
      AppComponent,
      AuthService,
      AuthHttp
  ],
  bootstrap: [ AppComponent ],
  imports : [
      BrowserModule,
      FormsModule,
      HttpModule,
      AuthModule,
      AppRoutingModule
  ],
  providers: [
      AuthService,
      AuthHttp
  ]
})
export class AppModule {
}

Answer 1

Working with atom (1.21.1 ia32)... i got the same error, even though i added a reference to my pipe in the app.module.ts and in the declarations within app.module.ts

solution was to restart my node instance... stopping the website and then doing ng serve again... going to localhost:4200 worked like a charm after this restart

Answer 2

You do not need the line:

import { SigninComponent, RegisterComponent } from './auth/auth.module';

in your app.component.ts as you already included the AuthModule in your app.module.ts . AutModule import is sufficient to use your component in the app.

The error that you get is a TypeScript error, not a Angular one, and it is correct in stating that there is no exported member, as it searches for a valid EC6 syntax for export, not angular module export. This line would thus work in your app.component.ts :

import { SigninComponent } from './auth/components/signin.component';

Answer 3

Also some of common cases :

maybe you export class with "default" prefix like so

export default class Module {}

just remove it

export class Module {}

this is solve the issue for me

Answer 4

对我来说，当我在单个.ts文件中有多个export语句时会出现这样的问题......

Answer 5

This error can also occur if your interface name is different than the file it is contained in. Read about ES6 modules for details. If the SignInComponent was an interface, as was in my case, then

SignInComponent

should be in a file named SignInComponent.ts .

Answer 6

I got similar issue. The mistake i made was I did not add service in the providers array in app.module.ts. Hope this helps, Thank You.

Answer 7

我遇到了同样的问题，我刚刚用新端口启动了应用程序，一切看起来都很好。

ng serve --port 4201

Answer 8

我在 app.routing.ts 或 app.module.ts 中的组件名称错误（区分大小写）。

Answer 9

In my module i am exporting classes this way:

export { SigninComponent } from './SigninComponent';
export { RegisterComponent } from './RegisterComponent';

This allow me to import multiple classes in file from same module:

import { SigninComponent, RegisterComponent} from "../auth.module";

PS: Of course @Fjut answer is correct, but same time it doesn't support multiple imports from same file. I would suggest to use both answers for your needs. But importing from module makes folder structure refactorings more easier.

Answer 10

就我而言，我重新启动了服务器并且它工作正常。