I want to use sqlite database in ionic2.
I could connect to the database and retrieved items data successfully in the following code. But I could have not push into this.items array.
Error says:
undefined is not an object(evaluating 'this.items')
Does anyone know what the problem is? I guess it's variable scope but I'm not sure.
import {Page, Platform} from 'ionic-angular';
declare var sqlitePlugin:any;
declare var plugins:any;
@Page({
templateUrl: 'build/pages/getting-started/getting-started.html'
})
export class GettingStartedPage {
items: Array<{title: string}>;
constructor(platform: Platform) {
platform.ready().then(()=>{
this.getData();
});
}
getData(){
sqlitePlugin.openDatabase({name: 'encrypted.db', key: 'Password', location: 'default'}, function(db) {
db.transaction(function(tx) {
var query: string = "SELECT * FROM items";
this.items = []; <-- error happens at this row.
tx.executeSql(query, [], function(tx, resultSet) {
//alert("name: " + resultSet.rows.item(0).name);
this.items.push({
title: resultSet.rows.item(0).name
});
}, function(error) {
alert('SELECT error: ' + error.message);
console.log('SELECT error: ' + error.message);
});
}, function(error) {
alert('transaction error: ' + error.message);
console.log('transaction error: ' + error.message);
}, function() {
console.log('transaction ok');
});
}, function(error){
alert('error' + error.message);
});
}
}
Use () =>
instead of function ()
With arrow functions this keeps pointing to the class instead the current function.
import {Page, Platform} from 'ionic-angular';
declare var sqlitePlugin:any;
declare var plugins:any;
@Page({
templateUrl: 'build/pages/getting-started/getting-started.html'
})
export class GettingStartedPage {
items: Array<{title: string}>;
constructor(platform: Platform) {
platform.ready().then(()=>{
this.getData();
});
}
getData(){
sqlitePlugin.openDatabase({name: 'encrypted.db', key: 'Password', location: 'default'}, (db) => {
db.transaction((tx) => {
var query: string = "SELECT * FROM items";
this.items = []; <-- error happens at this row.
tx.executeSql(query, [], (tx, resultSet) => {
//alert("name: " + resultSet.rows.item(0).name);
this.items.push({
title: resultSet.rows.item(0).name
});
}, (error) => {
alert('SELECT error: ' + error.message);
console.log('SELECT error: ' + error.message);
});
}, (error) => {
alert('transaction error: ' + error.message);
console.log('transaction error: ' + error.message);
}, () => {
console.log('transaction ok');
});
}, (error) =>{
alert('error' + error.message);
});
}
}
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