Victor's Notes

Fix AWS amplify angular app error on Access Denied error

When deploy your angular app on AWS amplify, the first landing page is able to load. However, when you defined a path in your router, and try to access it, you would hit Access Denied error: The solution is to navigate to AWS console,

Android

Write your Android app to run in background mode as a service

In some use cases, you may encounter a problem when your users put your app in the background mode or screen lock state, then your app functionality would be lost after several minutes. This would not be a good user experience, which may cause

Android

Caveat on Android in app browser

When you're developing a web application, you would need to consider browser compatibility issues. The problem I faced was an android in-app browser issue, which didn't test while in development but launched in production, causing many thousands of failure transaction. There were no clear

angular

Angular Error Explained: Expression Changed After It Has Been Checked Error

A colleague of mine encounters an error message while developing an Angular frontend app. The error message is like this: ExpressionChangedAfterItHasBeenCheckedError: Expression has changed after it was checked. Previous value 'null', Current value: 'true'.The scenario for this error is when he's developing a

angular

Writing unit test cases with Karma for angular component

I would like to convince you to start writing unit test cases for your angular web app. Shorten time to production is not an excuse to accumulate technical debts. There are many good reasons why you should start writing it: It helps you identify

django

Setup Django server with Apache virtual host and Python virtual environment

It took me a while to get everything works together, so I would like to document some of the steps and save you some time in the future. First of all, assuming that you already have your CentOS / Ubuntu instance running and python already

App Developer

Stop downloading app for anything and everything

Apps are irrelevant. Most of the tasks you perform in a native mobile app can be performed in a browser web app as well. We don’t need to download your stupid app because the browser is well suited as a replacement. One thing

Linux

Install Ubuntu 20.04 LTS on MacBookPro14,1

Ubuntu 20.04 just released and I can’t wait to try it out and install on my MacBook Pro 14.1 model. I am going to tell you what works and what doesn’t work, as well as any workaround to fix those

Browsers

Handle user close browser event with JavaScript

For some scenarios, you don’t want the user to close the browser and exit the journey. For example, if a user is filling in a form without saving or in the middle of payment transaction without complete, then you could prompt the

AWS

Import npm modules to AWS lambda function

When you create a node.js lambda function on Amazon Web Service (AWS), and start editing using the online editor, then you want to npm install and import a third party library, such as lodash, unfortunately there is no simple way to do it

WordPress

Fix Wordpress plugin installation permission issue

Problem: When I try to install a plugin at WordPress, I hit an error: Installation failed: Download failed. Destination directory for file streaming does not exist or is not writable. This is due to some permission problem when the content folder. I was editing

apache

Fix Wordpress with all pages returning 404 not found

Problem: I encounter a weird problem in WordPress, where the homepage is able to load properly, but all the pages are failing to load. An error page display: Not Found The requested URL was not found on this server. However, since the files were

apache

Fix endless redirection with https setting at Wordpress and using AWS load balancer

Problem: I set up a WordPress blog at 2 Amazon Web Service (AWS) EC2 instances at different availability zone. In front of them, a elastic load balancer (ELB) is set up, which redirect all HTTP port 80 requests to HTTPS port 443. Since the

Amazon

Install php7.2 instead of php5.4 on Amazon Linux 2

Problem: When you start a new Amazon Linux 2 AMI server, and try to install php via command: yum install php After install successfully and check the version, you would see php -v PHP 5.4.16 (cli) (built: Oct 31 2019 18:34:

Data Science

Reading large file using Node.js

I got a task to analyse a massive dataset of log files. When you open the file in Excel, it would simply freeze your laptop. Given the limitation of tools available, I try to parse the file using node.js script. Problem: To read

AWS

Migrate Wordpress MySQL to AWS RDS

In this article, I am going to explain how to migrate your WordPress local MySQL database to Amazon Web Service (AWS) Relational Database Service (RDS). Why would you want to do this? Because of the following benefits: It increases the performance since your database

Coding

Remove .DS_Store files in git

If you are a mac user and using git, you may accidentally commit a file with .DS_Store. Your windows colleague would be confused what does this files do and why do you commit it. First of all, what is .DS_Store file? DS

Coding

Remove .DS_Store files in git

If you are a mac user and using git, you may accidentally commit a file with .DS_Store. Your windows colleague would be confused what does this files do and why do you commit it. First of all, what is .DS_Store file? DS

Git

Git ignore already modified files

I encounter a rare scenario that there is a file modified, but I don’t want to commit this change on git. There are many ways to do such as .gitignore file, but it doesn’t work when the file already tracks.

Linux

Find and kill process locking specific port on Mac

Problem: Sometimes when you start a local node.js server, it may be stuck running at the background. When you try to start the server again, you will hit error saying that the port (for example 8080) is already is in used and locked:

Agile

How to work with Product Manager as a Software Engineer

I know that feel bro, cuz I’m also a software engineer. With years of experience, I have met some great Product Managers (PM) and a couple of bad ones. It is difficult to work closely with a bad PM every day, a bad

Adobe Experience Manager

Register Sling Servet in Adobe Experience Manager

In Adobe Experience Manager (AEM), a Sling servlet can be used for handling some RESTful request-responses ajax call. It is written in Java programming language and it can be registered as OSGi (Open Services Gateway Initiative) services. In order to trigger the script, there

AWS

Install Nextcloud on AWS EC2 and using S3 storage

I want more privacy, so I decided to minimize the use of Google products. I can replace Chrome with Firefox, replace Gmail with ProtonMail and replace Google Drive with Nextcloud. Nextcloud allows me to self-host of cloud storage and gives me control over my

PHP

Debug php code on browser

In javascript, you can console.log(‘whatever”) in your browser for troubleshooting. However, in php code, a little bit trick is required to do so. Here are the steps: function debug_to_console($data) { $output = $data; if (is_array($output)) $output = implode(',',

Linux

Install Ubuntu 19.10 on Macbook Pro 13,1

I was frustrated by the macOS Catalina, so I decided to switch to Ubuntu as the main operating system on my MacBook Pro, 13-inch version without touch bar. As a software developer, the macOS bundled a lot of tools with the Xcode which takes