import { NgModule, ModuleWithProviders } from '@angular/core'; import { CommonModule } from '@angular/common'; import { UserService } from './users.service'; import { ElectricityService } from './electricity.service'; import { StateService } from './state.service'; const SERVICES = [ UserService, ElectricityService, StateService, ]; @NgModule({ imports: [ CommonModule, ], providers: [ ...SERVICES, ], }) export class DataModule { static forRoot(): ModuleWithProviders { return { ngModule: DataModule, providers: [ ...SERVICES, ], }; } }