Using IONIC Storage Service, how to get and return stored JSON data?

Question

I’m new to Ionic.

I'm able to store A JSON object (data) using IONIC Storage Service; however, when I try to retrieve the JSON data, I get undefined.

I appreciate any help on this - below is my code:

Provider: storage-service.ts: I’m able to store and output data, but I cannot return the data:

import {Injectable} from '@angular/core';
import { Storage } from '@ionic/storage';

@Injectable()
export class StorageService {

constructor(public storage: Storage){}

public storeData (data) {
    this.storage.set('data', data);
}

public getStoredData() {
         this.storage.get('data').then((val) => {
        console.dir(val);  //****** this outputs the object.
        return val;  //***** this returns undefined
        });
  }
 }

my-page.ts:

import {StorageService} from "../../providers/storage-service";

constructor(public storageService: StorageService) {

    //***** this outputs undefined, what I'm doing wrong?
    console.dir(this.storageService.getStoredData());
}

Any help on this is greatly appreciated.

Thank you

sebaferreras · Accepted Answer · 2018-09-29 08:48:42Z

7

Since Ionic storage is based on promises, you need to return that promise in the service:

public getStoredData() {
  return this.storage.get('data').then((val) => { // <-- Here!
    console.dir(val);
    return val;
  });
}

And also use then to get the value in your page

import { StorageService } from "../../providers/storage-service";

constructor(public storageService: StorageService) {

  this.storageService.getStoredData().then(data => {
    console.dir(data); // <-- Like this!
  });

}

Here you can find some more information about how to use promises.

answered Sep 29, 2018 at 8:48

sebaferreras

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3 Comments

Bernard K. Over a year ago

Thank you, this worked, but my code looks messy. Is there a better way to do this:

constructor(public storageService: StorageService) {         this.storageService.getStoredData()             .then(data => {                 let hash = data.hash;                 let params = {'user_hash': user_hash};                 this.eventService.getEvents(headers, params)                     .subscribe((data: any) => {                             this.events = data;                         },                         (error: any) => {                         });              });     } }

sebaferreras Over a year ago

I think your code looks good. It's hard to know without some more context to be honest.

Perumal Samy S Over a year ago

Storageservice.ts loadData(key:string) { return this.storage.get(key).then((val) => { return val; }); } home.ts

this.interservice.loadData('auth').then((res) => {           this.activeuser = res;         });         console.log("Home",this.activeuser)

console return undefined. what's my mistake.

Sajeetharan · Accepted Answer · 2018-09-29 08:37:18Z

0

You need to return

public getStoredData() {
  return this.storage.get('data').then((val) => {
           return val;  
   });
  }
 }

answered Sep 29, 2018 at 8:37

Sajeetharan

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