Eror: Unexpected value 'undefined' exported by the module 'MaterialComponentsModule'

问题

I want to make a weather forecast card like this image.

But, I got this error Unexpected value 'undefined' exported by the module 'MaterialComponentsModule' when I compile. this error occurred. This is the DEMO and code as your reference.

Component Module

import { NgModule } from '@angular/core';
import { CommonModule } from '@angular/common';
import {
  MatAutocompleteModule,
  MatButtonModule,
  MatButtonToggleModule,
  MatCardModule,
  MatCheckboxModule,
  MatChipsModule,
  MatDatepickerModule,
  MatDialogModule,
  MatExpansionModule,
  MatGridListModule,
  MatIconModule,
  MatInputModule,
  MatListModule,
  MatMenuModule,
  MatNativeDateModule,
  MatPaginatorModule,
  MatProgressBarModule,
  MatProgressSpinnerModule,
  MatRadioModule,
  MatRippleModule,
  MatSelectModule,
  MatSidenavModule,
  MatSliderModule,
  MatSlideToggleModule,
  MatSnackBarModule,
  MatSortModule,
  MatTableModule,
  MatTabsModule,
  MatToolbarModule,
  MatTooltipModule,
  MatStepperModule,
} from '@angular/material';

@NgModule({
  imports: [
    CommonModule
  ],
  exports: [
    CommonModule,
    MatAutocompleteModule,
    MatButtonModule,
    MatButtonToggleModule,
    MatCardModule,
    MatCheckboxModule,
    MatChipsModule,
    MatDatepickerModule,
    MatDialogModule,
    MatExpansionModule,
    MatGridListModule,
    MatIconModule,
    MatInputModule,
    MatListModule,
    MatMenuModule,
    MatNativeDateModule,
    MatPaginatorModule,
    MatProgressBarModule,
    MatProgressSpinnerModule,
    MatRadioModule,
    MatRippleModule,
    MatSelectModule,
    MatSidenavModule,
    MatSliderModule,
    MatSlideToggleModule,
    MatSnackBarModule,
    MatSortModule,
    MatTableModule,
    MatTabsModule,
    MatToolbarModule,
    MatTooltipModule,
    MatStepperModule
  ]
})
export class MaterialComponentsModule { }

AppModule

import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';
import { FormsModule } from '@angular/forms';
import { HttpClientModule } from '@angular/common/http';
import { BrowserAnimationsModule } from '@angular/platform-browser/animations';
import { MaterialComponentsModule } from './material-components.module';

import { environment } from './environments/environment';
import { GeolocationService ,
  TransportService,
  WeatherService,
  CitiesService,
  ModalService
} from './services';

import { AppComponent } from './app.component';
import {
  MainComponent,
  ModalComponent,
  CitySelectorComponent,
  CityInfoComponent,
  CitiesListComponent,
  WeatherDescriptionComponent,
  WeatherItemComponent,
  ForecastDescriptionComponent
} from './components';

@NgModule({
  declarations: [
    AppComponent,
    MainComponent,
    ModalComponent,
    CitySelectorComponent,
    CityInfoComponent,
    CitiesListComponent,
    WeatherDescriptionComponent,
    WeatherItemComponent,
    ForecastDescriptionComponent
  ],
  imports: [
    BrowserModule,
    FormsModule,
    HttpClientModule,
    BrowserAnimationsModule,
    MaterialComponentsModule
  ],
  providers: [
    GeolocationService,
    TransportService,
    WeatherService,
    CitiesService,
    ModalService
  ],
  entryComponents: [
    ModalComponent,
    CitySelectorComponent
  ],
  bootstrap: [AppComponent]
})
export class AppModule { }

Hope you all can help me. Thanks in advance

回答1:

You have incompatible dependencies

@angular/core@8.0.0 vs @angular/material@9.0.0

Angular 9 is comming to stackblitz but it doesn't work yet.

So the solution is to use version 8 of @angular/material package.

Forked Stackblitz

Note for Angular material 9:

Components in Material 9 version can no longer be imported through "@angular/material". Use the individual secondary entry-points, such as @angular/material/button.

import {A11yModule} from '@angular/cdk/a11y';
import {ClipboardModule} from '@angular/cdk/clipboard';
import {DragDropModule} from '@angular/cdk/drag-drop';
import {PortalModule} from '@angular/cdk/portal';
import {ScrollingModule} from '@angular/cdk/scrolling';
import {CdkStepperModule} from '@angular/cdk/stepper';
import {CdkTableModule} from '@angular/cdk/table';
import {CdkTreeModule} from '@angular/cdk/tree';
import {MatAutocompleteModule} from '@angular/material/autocomplete';
import {MatBadgeModule} from '@angular/material/badge';
import {MatBottomSheetModule} from '@angular/material/bottom-sheet';
import {MatButtonModule} from '@angular/material/button';
import {MatButtonToggleModule} from '@angular/material/button-toggle';
import {MatCardModule} from '@angular/material/card';
import {MatCheckboxModule} from '@angular/material/checkbox';
import {MatChipsModule} from '@angular/material/chips';
import {MatStepperModule} from '@angular/material/stepper';
import {MatDatepickerModule} from '@angular/material/datepicker';
import {MatDialogModule} from '@angular/material/dialog';
import {MatDividerModule} from '@angular/material/divider';
import {MatExpansionModule} from '@angular/material/expansion';
import {MatGridListModule} from '@angular/material/grid-list';
import {MatIconModule} from '@angular/material/icon';
import {MatInputModule} from '@angular/material/input';
import {MatListModule} from '@angular/material/list';
import {MatMenuModule} from '@angular/material/menu';
import {MatNativeDateModule, MatRippleModule} from '@angular/material/core';
import {MatPaginatorModule} from '@angular/material/paginator';
import {MatProgressBarModule} from '@angular/material/progress-bar';
import {MatProgressSpinnerModule} from '@angular/material/progress-spinner';
import {MatRadioModule} from '@angular/material/radio';
import {MatSelectModule} from '@angular/material/select';
import {MatSidenavModule} from '@angular/material/sidenav';
import {MatSliderModule} from '@angular/material/slider';
import {MatSlideToggleModule} from '@angular/material/slide-toggle';
import {MatSnackBarModule} from '@angular/material/snack-bar';
import {MatSortModule} from '@angular/material/sort';
import {MatTableModule} from '@angular/material/table';
import {MatTabsModule} from '@angular/material/tabs';
import {MatToolbarModule} from '@angular/material/toolbar';
import {MatTooltipModule} from '@angular/material/tooltip';
import {MatTreeModule} from '@angular/material/tree';

来源：https://stackoverflow.com/questions/60161244/eror-unexpected-value-undefined-exported-by-the-module-materialcomponentsmod