Coding

Ever since I advanced beyond the “hello worlds” of Java, I had never stopped coding. This section is for documenting code usages that I had employed while solving the technological problems that I had encountered.

How to use your Raspberry Pi for Python development

Since its inception, the Raspberry Pi had progressed by leaps and bounds. Indeed, one of the reasons why we want to get a Raspberry Pi is its versatility. Apart from the huge selection of hardware, there are many Python libraries for you to build Raspberry Pi applications.

If you want to build something out of a Raspberry Pi, then you will benefit from setting up one for Python development.

Even if you do not build Raspberry Pi projects for a living, setting up a Raspberry Pi Python developer machine can be useful. For example, you may be a Solutions Engineer who build proof of concepts for demo purposes. In this case, you can build your demos with Python and run them on your Raspberry Pi.

If you are thinking of using Raspberry Pi for Python development, then this post is a reference for you.

How to get an Access Token to integrate with PayPal REST APIs in Python

Before you can integrate with PayPal via the REST APIs, you will need to obtain an access token.

Given that REST APIs is agnostic to programming languages, you can use a programming language of your choice to get the Access Token.

In case you are wondering how you can get an Access Token to integrate with PayPal REST APIs in Python, this is how you can do so.

How to prevent “Uncaught ReferenceError: jQuery / $ is not defined”

When you want to build a microsite, jQuery can help you simplify client side interactivity. If you build your website with WordPress, then you will be able to use jQuery in the custom theme that you are building.

Since you will base your site interactivity on jQuery, you may write JavaScript codes that throw the following error:

Uncaught ReferenceError: jQuery / $ is not defined.

In some cases, the error may appear randomly, making it hard to detect.

So how can we prevent our JavaScript codes from throwing a “Uncaught ReferenceError: jQuery / $ is not defined”?

How to use pycrypto, python-qrcode and Flask-RESTPlus to create QR codes that can send encrypted data to an endpoint

If you want to direct someone to a web page without saying a word, then you can use QR codes to do so.

For example, your QR code reader will direct your phone’s browser to visit our home page when you scan the following QR Code:

Techcoil home page QRCode

Given that, you can use QR codes to send HTTP requests to an endpoint of your HTTP server. In addition, you can embed data that you wish to send to the endpoint in the QR codes.

With this in mind, let’s look at how we can use pycrypto, python-qrcode and Flask-RESTPlus to create QR codes that can send encrypted data to an endpoint.

How to use threading.Condition to wait for several Flask-APScheduler one-off jobs to complete execution in your Python 3 application

Previously, I discussed how to use Flask-APScheduler in your Python 3 Flask application to run multiple tasks in parallel, from a single HTTP request.

When we run jobs as discussed in that post, jobs are ran once by the underlying ApScheduler instance. In addition, our Flask endpoint return the HTTP response back to the HTTP client as soon as the jobs are scheduled.

If we do not want the HTTP client to know the outcome of the jobs within that HTTP call, then we are good. But what if we want to include any errors that the jobs encounter in the same HTTP response?

In such a situation, we will need a mechanism to wait for the one-off jobs to complete execution before returning that response.

Given that in mind, this post shows how we can use threading.Condition to wait for several Flask-APScheduler one-off jobs to complete execution.

How to create an interval task that runs periodically within your Python 3 Flask application with Flask-APScheduler

Previously, I talked about how to use Flask-APScheduler in your Python 3 Flask application to run multiple tasks in parallel, from a single HTTP request.

If you wish to run long running tasks triggered by an HTTP request, then that post will help you do so.

However, what if you want to run jobs periodically without blocking your Flask HTTP server from serving HTTP requests?

In this case, you will want to run an interval task with Flask-APScheduler.

Given that, let’s look at how we can use Flask-APScheduler to create an interval task within your Python 3 Flask application.

How to post JSON data to a HTTP server endpoint from your ESP32 development board with ArduinoJson

When sending data from your ESP32 development board, you may choose to send the data in JSON.

In such a situation, you can consider using ArduinoJson to help you construct the JSON data.

Given that, let us look at how we can post JSON data to a HTTP server endpoint from a ESP32 development board with ArduinoJson.