SQLite in Ionic 3 getting data null after navigate to another page - sqlite

Question

Please help me. I've made Database Provider to connect with SQLite in ionic 3. When i want to get the data rows it's always getting null but when I check data length it has 1
This is my DatabaseProvider
import { Injectable } from '#angular/core';
import { Platform } from 'ionic-angular';
import { SQLite, SQLiteObject } from '#ionic-native/sqlite';
import { BehaviorSubject } from 'rxjs/BehaviorSubject';
import { Storage } from '#ionic/storage';
#Injectable()
export class DatabaseProvider {
private db: SQLiteObject;
private databaseReady: BehaviorSubject<boolean>;
constructor(private storage: Storage, private sqlite: SQLite, private platform: Platform) {
this.databaseReady = new BehaviorSubject(false);
this.platform.ready().then(() => {
this.sqlite.create({
name: 'takia.db',
location: 'default'
}).then((database: SQLiteObject) => {
this.db = database;
this.storage.get('database_filled').then(val => {
if (val) {
this.databaseReady.next(true);
} else {
this.initDB();
}
});
}).catch(e => { console.log(e); });
});
}
initDB(){
this.db.executeSql('CREATE TABLE IF NOT EXISTS users(user_id INTEGER PRIMARY KEY, username TEXT, email TEXT, password TEXT)', {})
.then(res => {
this.db.executeSql('INSERT INTO users VALUES(NULL,?,?,?,?)',['admin','admin.#email.com','password'])
.then(res => {
this.databaseReady.next(true);
this.storage.set('database_filled', true);
}).catch(e => {
console.log(e);
});
}).catch(e => {
console.log(e)
});
this.db.executeSql('CREATE TABLE IF NOT EXISTS questions(user_id INTEGER PRIMARY KEY, username TEXT, email TEXT, password TEXT)', {})
.then(res => {
this.db.executeSql('INSERT INTO users VALUES(NULL,?,?,?,?)',['admin','admin.tazkiaiibs.sch.id','bismillah'])
.then(res => {
this.databaseReady.next(true);
this.storage.set('database_filled', true);
}).catch(e => {
console.log(e);
});
}).catch(e => {
console.log(e)
});
}
getUser(){
return this.db.executeSql('SELECT user_id, username, email, password, COUNT(*) total FROM users', [])
.then(res => {
let users = [];
if (res.rows.length > 0) {
for (var i = 0; i < res.rows.length; i++) {
let row = res.rows.item(i);
users.push(row);
}
}
return users;
}, err => {
console.log('Error: ', err);
return [];
});
}
getDatabaseState() {
return this.databaseReady.asObservable();
}
}
and this is my code in component
constructor(public navCtrl: NavController,
public navParams: NavParams,
private dbProvider: DatabaseProvider,
private toastCtrl: ToastController) {
this.loadData();
}
loadData(){
this.dbProvider.getUser().then(data=>{
if(data.length>0){
this.id = data[0].id;
this.old_password = data[0].password;
this.username = data[0].username;
this.email = data[0].email;
let toast = this.toastCtrl.create({
message: 'ID '+data[0].username,
duration: 3000
});
toast.present();
}else{
let toast = this.toastCtrl.create({
message: 'No data'+data.length,
duration: 3000
});
toast.present();
}
});
}
When i run loadData function the length is not 0 but the data is null.

Answer 1

The comment under the question seemed to help, so I form it as an answer to hopefully collect some reputation points.
The problem seems to be a misformed SQL-query. The count(*) part makes the query return at least one row. Therefore the other fields might be NULL, when queried before data is added to the database.
The function "getUser" is called before the promise callback is executed.