Question

我有两个提供者。

AppStorage，负责设置和从存储中获取值。

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;

  } 
}

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] 
    }
  }

现在我将这两个注射剂添加到我的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 {}

但是当我运行应用程序时，oauthService的构造函数中的appStorage对象将变为未定义。你能告诉我我在做什么错，我只是在另一项服务中注入服务。

Answer 1

OauthService 提供程序中的静态参数getter（参数）应包含您注入构造函数的所有提供程序。但是，您只注入了 Http 提供商，但没有注入 AppStorage 提供商。我在下面修改了相应的代码：

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]
    }
}

Ionic2 / Angular2应用程序中的提供程序

1 个答案: