Category: python

QR code generator and reader/scanner in Python

Hi guys

Nowadays we see a lot of QR codes being used in commercial businesses, especially for transaction. QR code generator can encode many different kinds of data, such as plain text, website link (http or https protocol), vcard, geolocation and call.

There are several standards of QR codes. According to Wikipedia, there are four layers of structure of a QR code, as shown in the image below:

I am going to write tutorial on how to generate QR codes using qrcode Python package available at the PyPi website.

Part 1: Generate QR code using qrcode

Install qrcode package by using pip:

pip install qrcode

You should have a new command ‘qr’ in the terminal. From terminal (if you’re in UNIX/Linux environment) or command prompt (Windows), type:

qr "https://naimibrahim.me" > qrcode.png

It should generate an image in PNG format with the generated text encoded, like below:

For more advanced usage, please refer to the documentation.

Part 2: Read/scan QR code using zbarlight

My choice of package to read QR image is zbar, and its wrapper – zbarlight.

Firstly, download zbar source ball from its website http://zbar.sourceforge.net/download.html and compile it, or use the existing binary for your operating system.

from PIL import Image
import zbarlight
import sys

if len(sys.argv) < 2:
    exit
file_path = sys.argv[1]
with open(file_path, 'rb') as image_file:
    image = Image.open(image_file)
    image.load()

codes = zbarlight.scan_codes('qrcode', image)
print('QR codes: %s' % codes)

Run the above qrcode_scanner.py script by executing:

python qrcode_scanner.py qrcode.png

The output should be:

QR codes: [b'https://naimibrahim.me']

Now, you can even set up a web service to generate QR codes from your visitors, or print QR codes on pamphlets based on requirements from your customers, or any other idea that you have 🙂

Django REST Framework over NodeJS for Backend RESTful API

As I write, I’m a backend team lead for a Singaporean startup that develop an e-commerce platform. We decide to use Django REST Framework over NodeJS as backend application for CRUD operations of models from the front-end side (mobile app).

Listed below are some of the reasons why Django REST Framework wins over NodeJS:

    1. Easily define models/classes and use of inheritance 
      class User(AbstractBaseUser, PermissionsMixin):
created = models.DateTimeField(default=timezone.now)
email = models.EmailField(unique=True, db_index=True)
username = models.CharField(max_length=50, unique=True, blank=False)
first_name = models.CharField(max_length=100, blank=False)
last_name = models.CharField(max_length=100, blank=False)
USERNAME_FIELD = 'username'
REQUIRED_FIELDS = ['email', 'first_name', 'last_name']

class Meta:
verbose_name = 'user'
verbose_name_plural = 'users'
db_table = 'users'

      Very fast prototyping, isn’t it?

    2. Systematic and neat API URLs configuration
      Unless you develop a very small app, you can manage the API URLs easily by importing each app module URL configuration file into the main app URL configuration file
    3. Easy database models/tables migration
      You modify a model and Django will create a migration file to alter your database table structure
    4. Many packages available
      Thousands of available modules or packages at https://pypi.python.org/pypi to shorten your time to develop software
    5. Use of Python
      Python is an easy-to-learn programming language. For example:
      # Print Fibonacci numbers less than 10:

      >>> # Fibonacci series:
... # the sum of two elements defines the next
... a, b = 0, 1
>>> while b < 10:
...     print(b)
...     a, b = b, a+b

There are some other advantages, you'll find out when you use it 🙂 .