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Inappropriate coding practices - Unnecessary imports

Need​

Elimination of unnecessary imports in the codebase

Context​

  • Usage of Python 3.0+ for developing Python applications
  • Usage of Django for building web applications in Python

Description​

Non compliant code​

from django.http import HttpResponse
from django.shortcuts import render, redirect
from django.contrib.auth import authenticate, login
from django.contrib.auth.models import User
from django.contrib import messages
from django.utils import timezone
from django.core.mail import send_mail
from django.conf import settings
from django.db import models

def login_view(request):
    if request.method == "POST":
        username = request.POST['username']
        password = request.POST['password']
        user = authenticate(request, username=username, password=password)
        if user is not None:
            login(request, user)
            return redirect('home')
        else:
            messages.error(request, 'Invalid username or password.')
    return render(request, 'login.html')

In the above code, multiple modules are imported from Django at the start of the file. However, not all of these modules are used in the code.

For example, HttpResponse, User, timezone, send_mail, settings, and models are all imported but are not used anywhere in the code.

This is an example of a bad coding practice because it unnecessarily loads these modules into memory, even though they are not used anywhere in the code. This can lead to increased memory usage and slower performance.

It is recommended to only import the modules that are actually used in the code. This keeps the code cleaner, easier to understand, and more efficient in terms of memory usage and performance.

Steps​

  • Identify the unused imports in the code. In this case, the unused imports are: HttpResponse, User, timezone, send_mail, settings, and models.
  • Remove these unused imports from the code. This will reduce the load of the application as it will not have to load these unnecessary modules.
  • After removing the unused imports, test the application to ensure that it still works as expected. If there are any issues, they may be due to other parts of the code relying on these imports, in which case you will need to adjust the code accordingly.

Compliant code​

from django.shortcuts import render, redirect
from django.contrib.auth import authenticate, login
from django.contrib import messages

def login_view(request):
    if request.method == "POST":
        username = request.POST['username']
        password = request.POST['password']
        user = authenticate(request, username=username, password=password)
        if user is not None:
            login(request, user)
            return redirect('home')
        else:
            messages.error(request, 'Invalid username or password.')
    return render(request, 'login.html')

The updated code removes the unused imports from the original code. The unused imports that were removed include: HttpResponse, User, timezone, send_mail, settings, and models.

These imports were not being used in the code, and removing them reduces the load of the application as it will not have to load these unnecessary modules.

The remaining imports are necessary for the login_view function to work. The render and redirect functions from django.shortcuts are used to render the login page and redirect the user after successful login, respectively. The authenticate and login functions from django.contrib.auth are used to authenticate the user's credentials and log the user in. The messages module from django.contrib is used to display error messages when the login fails.

After removing the unused imports, it's important to test the application to ensure that it still works as expected. If there are any issues, they may be due to other parts of the code relying on these imports, in which case you will need to adjust the code accordingly.

References​

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