Angular 4：错误：没有 AngularFireDatabase 的提供者

Question

我已经尝试过post 的解决方案，但都没有奏效。几周前，我使用的是版本 4，并且在一个非常相似的项目中，这段代码正在运行，但现在我在尝试获取数据时遇到了这个控制台错误：

Error: No provider for AngularFireDatabase!
at injectionError (core.es5.js:1169)
at noProviderError (core.es5.js:1207)
at ReflectiveInjector_.webpackJsonp.../../../core/@angular/core.es5.js.ReflectiveInjector_._throwOrNull (core.es5.js:2649)
at ReflectiveInjector_.webpackJsonp.../../../core/@angular/core.es5.js.ReflectiveInjector_._getByKeyDefault (core.es5.js:2688)
at ReflectiveInjector_.webpackJsonp.../../../core/@angular/core.es5.js.ReflectiveInjector_._getByKey (core.es5.js:2620)
at ReflectiveInjector_.webpackJsonp.../../../core/@angular/core.es5.js.ReflectiveInjector_.get (core.es5.js:2489)
at resolveNgModuleDep (core.es5.js:9492)
at _createClass (core.es5.js:9529)
at _createProviderInstance$1 (core.es5.js:9503)
at resolveNgModuleDep (core.es5.js:9488)

这是我的服务.ts

    import { Injectable } from '@angular/core';
import { AngularFireDatabase, FirebaseListObservable, FirebaseObjectObservable } from 'angularfire2/database-deprecated';
import { Observable } from 'rxjs';
import { User } from '../models/users';

@Injectable()
export class UserService {

 users: FirebaseListObservable<any[]>;
  user: FirebaseObjectObservable<any>;

  constructor(public af:AngularFireDatabase) { 

    this.users = this.af.list('/users') as FirebaseListObservable<User[]>;
  }

  getUsers(){
    console.log(this.user);
    return this.user;
  }

}

接收数据的组件：

import { Component, OnInit } from '@angular/core';
import { UserService } from '../../services/user.service';
import { User } from '../../models/users';

@Component({
  selector: 'app-body',
  templateUrl: './body.component.html',
  styleUrls: ['./body.component.scss']
})
export class BodyComponent implements OnInit {
  user:User;

  constructor(public userService:UserService) { 

  }

  ngOnInit() {
    this.userService.getUsers().subscribe(users => {
      this.user = users;

    });

  }

还有 app.module.ts...

import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';
import { RouterModule, Routes } from '@angular/router';


import { AppComponent } from './app.component';
import { NavbarComponent } from './components/navbar/navbar.component';
import { BodyComponent } from './components/body/body.component';
import { FormsModule }   from '@angular/forms';
import { PlaygroundComponent } from './components/playground/playground.component';

// AngularFire Imports

import { AngularFireDatabase } from 'angularfire2/database';
import { AngularFireAuth } from 'angularfire2/auth';
import { AngularFireModule } from 'angularfire2';
import { AngularFireDatabaseModule } from 'angularfire2/database';

import { UserService } from './services/user.service';

const appRoutes: Routes = [
  {path:'', component:BodyComponent}
];

export const firebaseConfig = {
  apiKey: "AIzaSyD3KWZMx0ZJpZxXMCqtIrP-VvXE1SgXZoA",
  authDomain: "myfirstproject-d1c75.firebaseapp.com",
  databaseURL: "https://myfirstproject-d1c75.firebaseio.com",
  storageBucket: "myfirstproject-d1c75.appspot.com",
  messagingSenderId: "1027141777108"
}




@NgModule({
  declarations: [
    AppComponent,
    NavbarComponent,
    BodyComponent,
    PlaygroundComponent
  ],
  imports: [
    BrowserModule,
    FormsModule,
    RouterModule.forRoot(appRoutes),
    AngularFireModule.initializeApp(firebaseConfig),
    AngularFireDatabaseModule

  ],
  providers: [
    AngularFireAuth,
    AngularFireDatabase,
    UserService

  ],
  bootstrap: [AppComponent]
})
export class AppModule { }

如果有人能告诉我这里缺少什么，我真的很感激。该应用程序编译但随后我得到一个白屏和控制台中的错误而不是用户数组......谢谢！

Answer 1

只需将其从提供程序中删除并导入到您的组件中，

 providers: [
   // AngularFireAuth,
   // AngularFireDatabase,
    UserService
  ],

编辑

imports: [
    BrowserModule,
    FormsModule,
    RouterModule.forRoot(appRoutes),
    AngularFireModule.initializeApp(firebaseConfig),
    AngularFireDatabaseModule,
    AngularFireAuthModule

  ]