API调用不会在ngrx-angular6中发生

import { Injectable } from '@angular/core';
import { Actions, Effect, ofType } from '@ngrx/effects';
import { Observable, of } from 'rxjs';
import { catchError, map, mergeMap } from 'rxjs/operators';

import { ApiService } from './api.service';
import { LoadData, LoadDataSuccess, LoadDataFailure } from './data.actions';

@Injectable()
export class DataEffects {
  constructor(private actions$: Actions, private apiService: ApiService) {}

  @Effect()
  loadData$: Observable<any> = this.actions$.pipe(
    ofType<LoadData>(DataActionTypes.LoadData),
    mergeMap(() =>
      this.apiService.getData().pipe(
        map(data => new LoadDataSuccess(data)),
        catchError(error => of(new LoadDataFailure(error)))
      )
    )
  );
}

import { Injectable } from '@angular/core';
import { HttpClient } from '@angular/common/http';
import { Observable } from 'rxjs';

@Injectable()
export class ApiService {
  constructor(private http: HttpClient) {}

  getData(): Observable<any> {
    return this.http.get('https://api.example.com/data');
  }
}

import { EffectsModule } from '@ngrx/effects';
import { StoreModule } from '@ngrx/store';

import { DataEffects } from './data.effects';
import { dataReducer } from './data.reducer';
import { ApiService } from './api.service';

@NgModule({
  imports: [
    StoreModule.forRoot({ data: dataReducer }),
    EffectsModule.forRoot([DataEffects])
  ],
  providers: [ApiService]
})
export class AppModule {}