Coding

How to paginate MongoEngine records in your Python 3 Flask application

Flask and MongoEngine help makes development work easier.

One common task in the development of backend applications is the pagination of database records. Without pagination, the application server can run out of memory while generating a response from the database records.

This post discusses a way to paginate MongoEngine records in your Python 3 Flask application using the facilities provided by the Flask-MongoEngine extension.

How to deploy Python 3 Flask application on Raspberry Pi 3 with Raspbian Stretch Lite, Nginx, Supervisor, Virtualenv and Gunicorn

Raspberry Pi 3 Model B boards make good gifts for programmers and if someone had gifted you with one, you may want to use it as a control center for interacting with various IoT sensors and devices at home.

In such a situation, you may want to build a Python 3 Flask application to present the web interface for accessing the control center.

After you had built that Python 3 Flask application, the next step will be to deploy it on your Raspberry Pi 3 for serving HTTP requests.

This post discusses how you can deploy a Python 3 Flask application on Raspberry Pi 3 with Raspbian Stretch Lite, Nginx, Virtualenv and Gunicorn.

How to enable authenticated MongoDB access for Flask-MongoEngine applications

After having a first look at MongoDB more than 5 years back, I told myself that I will use MongoDB to realise the next functionality of Techcoil.

With exposure to Python 3, Flask and MongoEngine in 2017, I had acquired the skills to build a microsite to recommend gift ideas. This microsite uses MongoDB to store the gift recommendation data.

With Flask and MongoEngine, development of this microsite did not take too much leisure time. With MongoDB not enforcing authentication, there were not much hindrance in setting up the development environment for this microsite.

However, this free-for-all mode of accessing MongoDB is not recommended for production environments. Without authentication, it is easier for ill-intentioned people to mess up the backend database.

To ensure that I have a go-to post for implementing authenticated access to MongoDB backed projects in the future, I document the steps needed for Flask-MongoEngine applications to access MongoDB instances with access control turned on.

How to send an HTTP request to a HTTP Basic Authentication endpoint in Java without using any external libraries

One common task for Java developers is to write codes that communicate with API endpoints. Chances are these endpoints could use HTTP Basic Authentication for authenticating the HTTP request sender.

Although there are good libraries to help us craft and send HTTP requests to a web server in Java, I prefer to use the Java core library so as to keep my Java program lightweight.

Referencing my earlier post on how to construct a HTTP request to an endpoint with HTTP basic authentication, this post documents how to send an HTTP request to a HTTP Basic Authentication endpoint in Java without using any external libraries.

How to construct a HTTP request to an endpoint with HTTP Basic Authentication

The HTTP basic authentication is a mechanism commonly used by web servers to authenticate the sender of a HTTP request. Such a mechanism is usually used to guard server endpoints that are meant to be accessed programmatically.

Almost every new project that I got my hands on required me to create client side coding for accessing server endpoints that use HTTP basic authentication for authenticating the HTTP request sender.

To have a quick reference on how to construct a HTTP request to an endpoint with HTTP basic authentication, I created this post to as a documentation. The steps are agnostic to any programming languages.

How to reflect cart count at the cart icon as and when products are added or removed from the cart in WooCommerce

Although there is a hassle free option of using WooCommerce.com as your e-commerce store, you may prefer to host your own.

If you are familiar with WordPress and wish to host your e-commerce website, WooCommerce is also available as a WordPress plugin that augments WordPress with e-commerce website features.

Although more work needs to be done for self-hosted WordPress sites, we have the option of creating our own themes without having to pay additional charges on top of the web hosting fees.

When it comes to creating our own WooCommerce themes, one feature that we may want to implement would be to show the number of products that had been added to our WooCommerce cart near the shopping cart icon as and when products are added or removed from the cart.

This post documents how we can reflect cart count at the cart icon as and when products are added or removed from the WooCommerce shopping cart.

How to host your Python 3 Flask MVP with Supervisor on Ubuntu Server 16.04

Due to its minimalistic design, the Python Flask framework is ideal for building the web server layer of minimal viable products (MVP) to validate customers’ needs. However, development work is just one part of the user validation efforts. To ensure that our customer can access our Flask MVP and provide feedback as and when they are available, we will need to get it running with as a server daemon.

Supervisor is a convenient tool for running applications as a server daemon.

This post documents the steps that I took to host a Python 3 Flask MVP with Supervisor on an Ubuntu Server 16.04 instance.

How to serve static files with Python 3 + Flask

Python Flask is a good microframework for building a minimal viable product to validate our ideas on the Internet. A modern web application encompasses documents that tell the web browser how to build the visuals of our web application and communicate with our server backend. Such documents are usually static in nature and are served as they are to the web browser without any processing from the server end.

Comparing setting up an instance of the Nginx server with adding code in our Flask application, the latter can be a more convenient way for us to realise our minimal viable product. This post documents the proof of concept that I did to serve static files with Python 3 and Flask.

Examples on using the sum function in Octave

If you are taking Andrew Ng’s Machine Learning course on Coursera, the sum function is one of the functions that you will probably need to use to complete your assignments. Since the sum function can be counter intuitive in some cases, I document some of the examples that I had created while trying to get a better understanding of the sum function in Octave.