Saturday, June 24, 2017

Using Storage in Ionic 3

Ionic’s LocalStorage is now called simply Storage in Ionic 3 and behind the scenes Storage decides the best method to store the data. On mobile phones for example, SQLite is the preferred storage method. IndexedDB, WebSQL or localstorage is used in browsers for Progressive Web Apps.

InstallationFirst, install the SQLite Cordova plugin with this command:$ cordova plugin add cordova-sqlite-storage --save

Then install Storage. You can skip this step if you’re using a version or Ionic 3 greater than RC0, because Storage is now included automatically: $ npm install --save @ionic/storage

Importing + InjectingImport it in the appropriate module, the app root module for example:Module: app.module.tsimport { Storage } from '@ionic/storage'; @NgModule({ ... providers: [ Storage ] }) @NgModule({ ... providers: [ Storage ]})@NgModule({ ... providers: [ Storage ]})@NgModule({ ... providers: [ Storage ]})

Then inject it in the components that need it:Component: team.tsimport { Storage } from '@ionic/storage'; export class TeamPage {  constructor(public navCtrl: NavController, public storage: Storage) { }

UsageNow you’re ready to start using Storage’s set, get and remove methods. Let’s use a simple example where we have three methods, one that sets a team as a favorite, one that removes the team from the favorites and one that checks if a team is a favorite:Component: team.ts

fav() {`team ${ this.teamId }`, this.teamName);
this.favorite = true; }
removeFav() {`team ${ this.teamId }`); this.favorite = false; }
isFav() {'team ' + this.teamId).then((value) => { value ? this.favorite = true : this.favorite = false

}).catch(() => this.favorite = false); }In that example, the isFav method can be used in the ionViewWillEnter page lifecycle hook to determine if a team is already a favorite.