沒有UrlHelperService的提供商

Question

我只是運行一個如何構建離子應用程序的例子。然而，當我所服務的應用程序，我得到這個錯誤，

Error: No provider for UrlHelperService! 
at injectionError (http://localhost:8100/build/vendor.js:1527:90) 
at noProviderError (http://localhost:8100/build/vendor.js:1565:12) 
at ReflectiveInjector_._throwOrNull (http://localhost:8100/build/vendor.js:3007:19) 
at ReflectiveInjector_._getByKeyDefault (http://localhost:8100/build/vendor.js:3046:25) 
at ReflectiveInjector_._getByKey (http://localhost:8100/build/vendor.js:2978:25) 
at ReflectiveInjector_.get (http://localhost:8100/build/vendor.js:2847:21) 
at resolveNgModuleDep (http://localhost:8100/build/vendor.js:9847:25) 
at _createClass (http://localhost:8100/build/vendor.js:9898:32) 
at _createProviderInstance$1 (http://localhost:8100/build/vendor.js:9858:26) 
at resolveNgModuleDep (http://localhost:8100/build/vendor.js:9843:17) 

我app.module.ts

import { NgModule, ErrorHandler } from '@angular/core'; 
import {HttpModule} from '@angular/http'; 

import { BrowserModule } from '@angular/platform-browser'; 
import { IonicApp, IonicModule, IonicErrorHandler } from 'ionic-angular'; 
import { MyApp } from './app.component'; 

import { AboutPage } from '../pages/about/about'; 
import { ContactPage } from '../pages/contact/contact'; 
import { HomePage } from '../pages/home/home'; 
import { TabsPage } from '../pages/tabs/tabs'; 

import { StatusBar } from '@ionic-native/status-bar'; 
import { SplashScreen } from '@ionic-native/splash-screen'; 
import {LoginPage} from "../pages/login/login"; 
import {OAuthService} from "angular-oauth2-oidc"; 


@NgModule({ 
    declarations: [ 
    MyApp, 
AboutPage, 
ContactPage, 
HomePage, 
TabsPage, 
LoginPage 
    ], 
    imports: [ 
    BrowserModule, 
    HttpModule, 
    IonicModule.forRoot(MyApp) 
    ], 
    bootstrap: [IonicApp], 
    entryComponents: [ 
    MyApp, 
AboutPage, 
ContactPage, 
HomePage, 
TabsPage, 
LoginPage ], 
     providers: [ 
    OAuthService, 
    StatusBar, 
    SplashScreen, 
    {provide: ErrorHandler, useClass: IonicErrorHandler} 
    ] 
}) 
export class AppModule {} 

我app.component.ts

import { Component } from '@angular/core'; 
import { Platform } from 'ionic-angular'; 
import { StatusBar } from '@ionic-native/status-bar'; 
import { SplashScreen } from '@ionic-native/splash-screen'; 

import { TabsPage } from '../pages/tabs/tabs'; 
import { OAuthService } from 'angular-oauth2-oidc'; 
import { LoginPage } from '../pages/login/login'; 

@Component({ 
    templateUrl: 'app.html' 
}) 
export class MyApp { 
    rootPage:any = TabsPage; 

    constructor(platform: Platform, statusBar: StatusBar, splashScreen: 
SplashScreen, oauthService: OAuthService) { 
    if (oauthService.hasValidIdToken()) { 
     this.rootPage = TabsPage; 
    } else { 
     this.rootPage = LoginPage; 
    } 
    platform.ready().then(() => { 

    statusBar.styleDefault(); 
    splashScreen.hide(); 
    }); 
    } 
} 

我使用 離子框架：3.7.0 Ionic App腳本：3.0.0 Angular Core：4.4.3 Angular Compiler CLI：4.4.3 節點：6.11。 0 OS平臺：視窗10 導航平臺：Win32的

Answer 1

這個錯誤出現在你使用的是一些服務（在你的情況UrlHelperService）在您的應用程序，但還沒有把它添加到providers。

確保當您創建和在應用程序中使用任何服務，您必須將它們導入providers在@NgModule

import { SomeService } from "../services/some-service.service"; 

@NgModule({ 
     declarations: [ // Components ], 
     imports: [ // Modules ], 
     bootstrap: [IonicApp], 
     entryComponents: [// Entry Components], 
     providers: [ SomeService ] // <==== HERE 
}) 
export class AppModule {}