how to use sharedModule in angular2?

Question

I have one angular2 component which I want to share among multiple modules.

So I wrote below sharedModule ,

import { NgModule }      from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import {GenericComponent} from './generic/generic.component';
@NgModule({
  imports:      [ BrowserModule ],
  declarations: [ GenericComponent ],
  exports:      [ GenericComponent ]
})
export class SharedModule { }

then I added this sharedModule to multiple modules as below:

app.module.ts

import { NgModule }      from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import {SharedModule} from './shared.module';
import { AppComponent } from './app.component';
@NgModule({
  imports:      [ BrowserModule,SharedModule ],
  declarations: [ AppComponent ],
  exports:      [ AppComponent ],
  bootstrap: [AppComponent]
})
export class AppModule { }

I also added sharedModule to generic.module.ts similarly ,

generic.module.ts

import { NgModule }      from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import {SharedModule} from './shared.module';
@NgModule({
  imports:      [ BrowserModule,SharedModule ],
  declarations: [ //.. here I have added all the components that generic uses ]
})
export class GenericModule { }

but I am getting below error when I am trying to use generic component inside components of generic.module.ts

Unexpected value 'undefined' imported by the module 'GenericModule'

Answer 1

Here's the code from my app using a shared module:

App module:

import { AboutModule } from './about/about.module';
import { SharedModule }   from './shared/shared.module';
import { Menubar, MenuItem } from 'primeng/primeng';

@NgModule({
    imports: [ BrowserModule, RouterModule.forRoot(appRoutes), SharedModule.forRoot(), 
               HomeModule ],
    declarations: [ AppComponent ],
    bootstrap: [ AppComponent ],
    providers: [ appRoutingProviders ]

}) 

export class AppModule {} 

The home module:

import { SharedModule }   from '../shared/shared.module';
import {routing} from './home.routing'


@NgModule({
    imports: [ SharedModule, routing],
    declarations: [ HomeComponent, LoginComponent, RegisterComponent, VerifyComponent, 
                   VerifyEmailComponent, ForgotComponent, ForgotVerifyComponent, 
                   ChangeComponent, ChallengeComponent, LogoutComponent ], 
    bootstrap: [ HomeComponent ],
    providers: [ ]

}) 

export class HomeModule {} 

And the shared module:

@NgModule({
  imports: [CommonModule, RouterModule, MenubarModule, GalleriaModule, InputTextModule, PanelModule, ButtonModule,
            DropdownModule, DialogModule, AccordionModule, CalendarModule, SelectButtonModule, CheckboxModule,
            ProgressBarModule, DataTableModule],
  declarations: [ ErrorMessagesComponent, FoodDashboardComponent ],
  exports: [ CommonModule, ReactiveFormsModule, HttpModule, RouterModule,
            MenubarModule, GalleriaModule, InputTextModule, PanelModule, ButtonModule, DropdownModule, DialogModule, AccordionModule, CalendarModule,
            SelectButtonModule, CheckboxModule, DataTableModule, ProgressBarModule, ErrorMessagesComponent, FoodDashboardComponent ]
})

export class SharedModule {
  //
  static forRoot(): ModuleWithProviders {
    return {
      ngModule: SharedModule,
      providers: [SettingsService, AppMenuService, AuthorizationService, LoginService, RegisterService, ThemeService, ValidationService,
        NutritionixService, AuthGuardService, CalculationService, ChallengeService ]
    };
  }
}

I have more than 20 modules in my app and I use the shared module all over the place. This works just fine. Hope it helps.