离子存储以Aync方式获取值 [英] ionic storage getting values in Aync way

问题描述

我正在尝试在离子存储中获取2个值存储，但是该值以异步方式重新执行，并且在重试值之前发生请求

I am trying to get 2 values stores in ionic storage , but the value are retrived in async way and request is happening before the values are retrived

此处验证， url处于离子存储状态

Here Auth, url are in ionic storage

import { Injectable } from '@angular/core';
import { Http, Response } from '@angular/http';
import 'rxjs/add/operator/map';
import {Headers} from '@angular/http';
import { Storage } from '@ionic/storage';

/*
  Generated class for the SeasonService provider.

  See https://angular.io/docs/ts/latest/guide/dependency-injection.html
  for more info on providers and Angular 2 DI.
*/
@Injectable()
export class SeasonService {
Auth;
url;

  constructor(public http: Http, public storage: Storage) {
    console.log('Inside SeasonService constructor');

    this.storage.get('Auth').then((Auth) => {
      console.log('Retrived Auth is', Auth);
      this.Auth = Auth;

    } );
    this.storage.get('url').then((url) => {
      console.log('Retrived url is', url);
      this.url = url;
    } );
   }

  public getSeasonList() {

          console.log('Season Auth is', this.Auth);
          console.log('Season url is', this.url);
        const headers: Headers = new Headers();
        headers.append('Authorization', 'Basic ' + this.Auth);
        headers.append('Content-Type', 'application/json');
        return (this.http.get('http://' + this.url +'/Windchill/servlet/rest/rfa/instances?module=SEASON',
        {headers: headers}).
        map((response: Response) =>  response.json()));
      }
}

输出就像这样

Here
auth-service.ts:49 Headers {_headers: Map(2), _normalizedNames: Map(2)}
auth-service.ts:77 There
season-service.ts:19 Inside SeasonService constructor
season-service.ts:34 Season Auth is undefined
season-service.ts:35 Season url is undefined
season-service.ts:22 Retrived Auth is d2NhZG1pbjp3Y2FkbWlu
season-service.ts:27 Retrived url is 192.168.146.52
auth-service.ts:79 Your CSRF is laxYnd5XE6d/r+W655087+8dY5Irxc7do94fxLgvY5ImgNeIwsgI1bYaQdAzxZDM5sMZsqgbXppFntGDoJhrq+puJJROnN+N1MEcy7d4Js8ozs7Oxpwfpe0zRvcIktg=
auth-service.ts:82 Your Auth is d2NhZG1pbjp3Y2FkbWlu
auth-service.ts:85 Your url is 192.168.146.52

推荐答案

你必须等待两个承诺在制作之前得到解决请求。
首先将存储代码移至某些 init 方法。

You have to wait for both promise to get resolved before make request. First move your storage code to some init method.

public init(){

let promiseList: Promise<any>[] = [];
promiseList.push(
 this.storage.get('Auth').then((Auth) => {
      console.log('Retrived Auth is', Auth);
      this.Auth = Auth;

    } ));
promiseList.push(
    this.storage.get('url').then((url) => {
      console.log('Retrived url is', url);
      this.url = url;
    } ));

return Promise.all(promiseList);
}

现在在getSesonList之前调用init方法：

Now call init method before getSesonList as followed:

this.sessionService.init().then((values)=>{
this.sessionService.getSeasonList();
});

这将确保 getSeasonList 方法将在两个存储承诺得到解决后调用。

this will make sure that the getSeasonList method will be called after both storage promises get resolved.

显然你应该把一些错误处理代码放在你身上。

Obviously you should put some error handling code but its upon you.

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