创建了一个简单的组件，现在我得到一个关于提供程序的错误

Question

做这个项目，我创建了一个简单的组件来放置我的allert，现在我有这个错误，我不能解决：

StaticInjectorError(AppModule)DiscountAllertComponent: StaticInjectorError(Platform: core) DiscountAllertComponent : NullInjectorError:没有DiscountAllertComponent的提供者！

我像往常一样创建了组件，我不知道我必须做些什么来修复它！

组件：

import { Component, OnInit } from '@angular/core';
import {AngularFireDatabase} from '@angular/fire/database';
import {AlertController} from '@ionic/angular';
import {Router} from '@angular/router';

@Component({
  selector: 'app-discount-allert',
  templateUrl: './discount-allert.component.html',
  styleUrls: ['./discount-allert.component.scss'],
})
export class DiscountAllertComponent implements OnInit {

  constructor(
      // public af: AngularFireDatabase,
              public alertController: AlertController) { }

  ngOnInit() {}
}

组件模块：

mport {CUSTOM_ELEMENTS_SCHEMA, NgModule} from '@angular/core';
import {CommonModule} from '@angular/common';
import {SharedHeaderComponent} from './shared-header/shared-header.component';
import {AlertController, IonicModule} from '@ionic/angular';
import {UserInfoComponent} from './user-info/user-info.component';
import {AddressComponent} from './address/address.component';
import {FormsModule, ReactiveFormsModule} from '@angular/forms';
import {TranslateModule} from '@ngx-translate/core';
import {PasswordStrengthBarModule} from 'ng2-password-strength-bar';
import {SchedulerComponent} from './scheduler/scheduler.component';
import {OrderConfigurationComponent} from './order-configuration/order-configuration.component';
import {OrderComponent} from './order/order.component';
import {MenuComponent} from './menu/menu.component';
import {DishOptionsComponent} from './dish-options/dish-options.component';
import {PasswordResetComponent} from './password-reset/password-reset.component';
import {OrderResumeComponent} from './order-resume/order-resume.component';
import {PaymentMethodComponent} from './payment-method/payment-method.component';
import {OnlinePaymentComponent} from './online-payment/online-payment.component';
import {PipesModule} from '../pipes/pipes.module';
import {ChangePasswordComponent} from './change-password/change-password.component';
import {CardsManagerComponent} from './cards-manager/cards-manager.component';
import {LocationSelectComponent} from './location-select/location-select.component';
import {MbrefComponent} from './mbref/mbref.component';
import {MbwayComponent} from './mbway/mbway.component';
import {CardModule} from '../directives/card/module';
import {DiscountAllertComponent} from './discount-allert/discount-allert.component';

const COMPONENTS = [
  AddressComponent,
  CardsManagerComponent,
  ChangePasswordComponent,
  DishOptionsComponent,
  LocationSelectComponent,
  MbrefComponent,
  MbwayComponent,
  MenuComponent,
  OrderComponent,
  OrderConfigurationComponent,
  OrderResumeComponent,
  PasswordResetComponent,
  SchedulerComponent,
  SharedHeaderComponent,
  UserInfoComponent,
  PaymentMethodComponent,
  OnlinePaymentComponent,
  DiscountAllertComponent
];

@NgModule({
  declarations: [COMPONENTS],
  imports: [
    IonicModule,
    CardModule,
    CommonModule,
    FormsModule,
    PasswordStrengthBarModule,
    ReactiveFormsModule,
    TranslateModule,
    PipesModule,

  ],
  schemas: [CUSTOM_ELEMENTS_SCHEMA],
  exports: [COMPONENTS],
  entryComponents: [COMPONENTS],
})
export class ComponentsModule {
}

Answer 1

当您为页面创建组件时，您必须在所使用页面的声明：[]的.module.ts文件中声明它。例如：

declarations: [DiscountAllertComponent]

如果仍然不起作用，请尝试将其添加到：

  entryComponents: [DiscountAllertComponent]