My custom SQLite module ("DatabaseProvider") contains some essential methods for reading and writing data ("insertActivity" and "getData").
When I invoke the insertActivity() function, everything works smoothly. However, calling the getData() method triggers an unexpected error:
ERROR: TypeError: Cannot read property 'executeSql' of undefined
I am puzzled by this inconsistency since both functions are supposed to be equal, as well as the .ts files from where they are called.
This is how my database.ts looks like:
import { Injectable } from '@angular/core';
import { SQLite, SQLiteObject } from '@ionic-native/sqlite';
import { Http } from '@angular/http';
import 'rxjs/add/operator/map';
@Injectable()
export class DatabaseProvider {
// private storage: SQLite;
public db: SQLiteObject;
public isOpen: boolean;
public storage: any;
constructor(
public http: Http,
public database: SQLite,
) {
if (!this.isOpen) {
// create db and tables
this.database = new SQLite();
this.database.create({name: 'RLSDB', location: 'default'})
.then((db: SQLiteObject) => {
this.storage = db;
db.executeSql('create table if not exists LOGIN (id INTEGER PRIMARY KEY AUTOINCREMENT, sid TEXT, username TEXT, password TEXT, email TEXT, timestamp TEXT)', {}).then((data) => {
this.isOpen = true;
console.log('TABLE CREATED: ', data);
}, (error) => {
console.error("Unable to execute sql", error);
});
}).then(() => {
this.storage.executeSql('create table if not exists ACTIVITIES (id INTEGER PRIMARY KEY AUTOINCREMENT, activity_name TEXT, activity_datetime TEXT)', {});
this.isOpen = true;
}
);
}
}
public getData() {
return new Promise((resolve, reject) => {
this.storage.executeSql('SELECT * from ACTIVITIES', []).then((data) => {
let activityValues = [];
if (data.rows.length > 0) {
for(let i=0; i <data.rows.length; i++) {
activityValues.push(data.rows.item(i).activity_datetime);
}
}
return resolve(data);
}, (error) => {
return reject(error);
});
});
}
public insertActivity(
RLSActivity: string,
RLSActivityDatetime: any ) {
return new Promise((resolve, reject) => {
this.storage.executeSql("INSERT INTO ACTIVITIES (activity_name, activity_datetime) VALUES (?, ?)", [RLSActivity, RLSActivityDatetime]).then((data) => {
return resolve(data);
}, (error) => {
return reject(error);
});
});
}
}
The usage occurs in two sections: "modal-add" and "stats".
Here is my functional modal-add.ts file:
import { Component } from '@angular/core';
import { NavController } from 'ionic-angular';
import { IonicPage, NavParams, ViewController } from 'ionic-angular';
import { DiaryPage } from '../diary/diary';
import {Validators, FormBuilder, FormGroup } from '@angular/forms';
import { DatabaseProvider } from '../../providers/database/database';
@IonicPage()
@Component({
selector: 'page-modal-add',
templateUrl: 'modal-add.html',
})
export class ModalAddPage {
private activityForm: FormGroup;
constructor(
public navParams: NavParams,
private view: ViewController,
private navCtrl: NavController,
private formBuilder: FormBuilder,
public database: DatabaseProvider
) {
this.activityForm = this.formBuilder.group({
title: [''],
date: [''],
});
}
closeModal(){
const inputData = {
title: this.activityForm.value.title,
date: this.activityForm.value.date,
};
this.database.insertActivity(inputData.title, inputData.date);
(...)
}
}
However, the non-functional stats.ts file raises errors:
import { Component, ViewChild } from '@angular/core';
import { IonicPage, NavController, NavParams } from 'ionic-angular';
import { DiaryPage } from '../diary/diary';
import { DatabaseProvider } from '../../providers/database/database';
import { Chart } from 'chart.js';
@IonicPage()
@Component({
selector: 'page-stats',
templateUrl: 'stats.html'
})
export class StatsPage {
@ViewChild('lineCanvas') lineCanvas;
lineChart: any;
events: any;
constructor(
public navCtrl: NavController,
public navParams: NavParams,
private db: DatabaseProvider
) {
}
ionViewDidLoad() {
this.events = this.db.getData();
this.lineChart = new Chart(this.lineCanvas.nativeElement, {
(...) // logic to generate a chart
}
}
Any insights or suggestions on how to resolve this issue?
Your assistance is greatly appreciated.