Current user doesn't persist when reloading an app (Ionic2 + Parse Server) - authentication

Question

I'm currently working on Ionic 2 app with Parse Server backend.
I implemented signed up process. No problems here, everything works as expected: new account is created, user is logged in after sign up and current user exists.
Now I want to use current user and bypass sign up/login page next time user opens the app (if the user is already logged in ). The Parse documentation clearly states:
“It would be bothersome if the user had to log in every time they
open your app. You can avoid this by using the cached
current Parse.User object. Whenever you use any signup or login
methods, the user is cached in localStorage.”
In my case, however, I can't manage to make it work. I create current user according to Parse documentation during initialization process of the app:
var currentUser = Parse.User.current();
if (currentUser) {
// do stuff with the user
} else {
// show the signup or login page
}
Every time I open the app after successful sign up the current user is NULL.
Any ideas?

Answer 1

I kinda understand what's going on, but still don't understand why.
During signup or login Parse is supposed to save current user to local storage, but if local storage is not available for some reason, it saves it to memory map. And this is what happens in my case: Parse always saves current user to memory map, which is, of cause, temporary storage. Hence, every time I reload the app, Parse memory map is empty. I don't understand why in my environment Parse decides that local storage is unavailable. I couldn't find in the code where this decision is made. It seems to me that memory map is default (which is probably not true). Could it be that local storage functionality is not implemented yet in the open source version of Parse? Or does it have something to do with Ionic2 implementation?
Is there anybody out there from Parse team who is familiar with this part of Parse code?
Thanks.

Answer 2

Hi I use Local Storage.
import { Component } from '#angular/core';
import { NavController,Alert,Storage,LocalStorage } from 'ionic-angular';
import {HomePage} from'../home/home';
import {UserdetailPage} from'../userdetail/userdetail';
declare var require:any;
var Parse = require('parse/node');
#Component({
templateUrl: 'build/pages/user/user.html',
})
export class UserPage {
public currentUser:any;
public local:any;
username:string="";
password:string="";
repassword: string="";
sign:string = "SIGN IN";
constructor(private nav: NavController) {
Parse.initialize(XXXXX);
Parse.serverURL = 'XXXXXX';
this.local = new Storage(LocalStorage);
this.currentUser = this.local.get('userid');
console.log(this.currentUser);
}
signin(){
console.log("username:"+this.username);
console.log("password:"+this.password);
if(this.username!="" &&this.password!=""){
if(this.repassword!=""){
// Register User Session
this.register();
}
else if(this.repassword==""&&this.username!=""&&this.password!=""){
this.login();
}
}
}
changeSign(s:string){
console.log(s);
if(s!="")
this.sign = "SIGN UP (Register New Account)";
else
this.sign ="SIGN IN";
}
register(){
if(this.repassword==this.password){
var parseuser = new Parse.User();
parseuser.set("username",this.username);
parseuser.set("password",this.password);
parseuser.signUp(null, {
success:user=>this.registerSucessAlert(),
error: error=>this.registerFailAlert("Register Fail, The user name exists or Server is down")
});
}
else{
this.registerFailAlert("Password is not the same");
}
}
login(){
console.log("Login");
Parse.User.logIn(this.username, this.password, {
success:user=>this.loginSucessAlert(),
error:error=>this.loginFailAlert()
});
}
loginSucessAlert(){
this.currentUser = Parse.User.current().id;
this.local.set('userid',this.currentUser);
let alert = Alert.create({
title:'Login',
subTitle:'Hi '+this.username+', Press to Continue.',
buttons:[{text:'OaaaK',
handle:()=>{this.nav.setRoot(UserdetailPage);}}]
});
this.nav.present(alert);
}
loginFailAlert(){
let alert = Alert.create({
title:'Login',
subTitle:'Login Error',
buttons:['OK']
});
this.nav.present(alert);
}
registerSucessAlert(){
this.currentUser = Parse.User.current().id;
this.local.set('userid',this.currentUser);
let alert = Alert.create({
title:'Resgiter',
subTitle:'Thank you'+this.username+' for register, Press to Continue.',
buttons:['OK']
});
this.nav.present(alert);
}
registerFailAlert(err:string){
let alert = Alert.create({
title:'Register Fail',
subTitle:err,
buttons:['OK']
});
this.nav.present(alert);
}
}