Ionic2 / Angular2应用程序中提供程序内部的提供程序

Question

我有两个提供者。

1. AppStorage负责设置并从存储中获取值。

    import { Injectable } from '@angular/core'; import {Http, Headers, RequestOptions} from '@angular/http'; import {Observable} from 'rxjs/Rx'; import {Storage} from '@ionic/storage'; @Injectable() export class AppStorage { constructor(public http: Http, private storage:Storage) { console.log('Hello Appstorage Provider'); } setValue(key,value){ var setPromise = new Promise((resolve,reject)=>{this.storage.set(key,value).then((res)=>{ return resolve(res); }) }); return setPromise; }; getValue(key){ var getPromise = new Promise((resolve,reject)=>{this.storage.get(key).then((val)=>{ return resolve(val); }); }); return getPromise; } } 

2. OauthService是我的api服务。

    import {Http, Headers, RequestOptions} from '@angular/http'; import { Injectable, Inject} from '@angular/core'; import 'rxjs/add/operator/map'; import { AppStorage } from '../providers/appstorage'; @Injectable() export class OauthService{ http: Http; response :any; appStorage: AppStorage; static get parameters() { return [[Http]]; } constructor(http: Http,@Inject(AppStorage) appStorage: AppStorage){ this.http = http; this.appStorage = appStorage; setTimeout(()=>{ console.log('Hello OauthService Provider'+this.appStorage+"===="+this.http); },3000) //output - >Hello OauthService Providerundefined====[object Object] } } 

现在我将两者都添加到我的app.module

import { NgModule, ErrorHandler } from '@angular/core';
import { IonicApp, IonicModule, IonicErrorHandler } from 'ionic-angular';
import { MyApp } from './app.component';
import { LoginPage } from '../pages/login/login';
import { AppStorage } from '../providers/appstorage';
import { Storage } from '@ionic/storage';
import { OauthService } from '../providers/oauthservice';

@NgModule({
  declarations: [
    MyApp,
    LoginPage
  ],
  imports: [
    IonicModule.forRoot(MyApp)
  ],
  bootstrap: [IonicApp],
  entryComponents: [
    MyApp,
    LoginPage
  ],
  providers: [{provide: ErrorHandler, useClass: IonicErrorHandler},OauthService, Storage, AppStorage]
})
export class AppModule {}

但是，当我运行该应用程序时，oauthService的构造函数中的appStorage对象未定义。 您能告诉我我在做什么错吗，我只是在将服务注入另一个服务中。

Answer 1

OauthService提供程序中的静态参数getter（ parameters ）应包括您注入到构造函数中的所有提供程序。 但是，您只注入了Http提供程序，而没有注入AppStorage提供程序。 我已经相应地修改了以下代码：

import { Http } from '@angular/http';
import { Injectable } from '@angular/core';
import 'rxjs/add/operator/map';
import { AppStorage } from './appstorage';

@Injectable()
export class OauthService {

    response :any;

    static get parameters() {
        return [[Http], [AppStorage]];
    }

    constructor(private http: Http, private appStorage: AppStorage) {

        setTimeout(() => {
            console.log('Hello OauthService: appStorage=' + this.appStorage + ", http=" + this.http);
        }, 3000)
        //output - >Hello OauthService: appStorage=[object Object], http=[object Object]
    }
}