Why I Use MVCS in Django: A Clean Code Perspective

When I first started building Django apps a few years ago, I stuck to the traditional structure — MVC (Model–View–Controller), or as it’s known in Django, MVT (Model–View–Template). It worked well for simple projects, and I didn’t think much about architecture back then.

But as my apps became more complex, problems started creeping in. Business logic got tangled up in views, error handling became chaotic, and the separation of concerns practically disappeared. The system functioned, sure — but it felt lifeless. Everything was wired together in a fragile way, and maintaining it became a chore.

As I explored frameworks like Spring Boot and Golang for building web apps, I began to question like

• Why not MVCS — Model, View, Controller, and Service — in Django as well?

• Why does the traditional way of building Django apps seem to overshadow flexibility and make the structure feel so rigid, even though there’s room for more adaptable designs?

These questions led me to explore the MVCS architecture — an extension of the traditional MVC pattern — which introduces a dedicated Service layer to better organize business logic, handle errors more cleanly, and improve code maintainability. Let’s dive into what MVCS is and why it might be a game-changer for Django projects.

What is MVCS?

MVCS stands for Model–View–Controller–Service. It builds upon the traditional MVC pattern by introducing a Service layer to handle business logic, making the architecture cleaner, more modular, and easier to scale.

Here's a quick breakdown:

• Model: Represents the data layer - Django's database schema
• View: In Django, this refers to the logic that receives requests and sends responses (typically a JSON Response in case of APIs or Renders HTML pages in case of web pages)
• Controller: Although Django handles routing internally, the views often act as controllers by directing requests and orchestrating logic.
• Service: This layer is a dedicated layer, where the core business logic lives. Instead of dumping complex operations into views, we push them into services — making the views thinner and the codebase easier to test and maintain.

Why this Service Layer?

In traditional Django apps, views often end up bloated — juggling validation, queries, processing, and response generation. As projects scale, this becomes increasingly difficult to manage.

Introducing a Service layer gives us:

• Clean, focused views
• Centralized and reusable business logic
• Better unit testing capabilities
• A structure that aligns with SOLID principles, especially Single Responsibility

Case Study: Course Management System

To try out MVCS in Django, I built a Course Management System. While real university-grade systems are incredibly complex — involving scheduling engines, messaging workflows, and granular access control — I narrowed my project down to a few essential features to focus on architectural clarity over scale.

Use Cases Considered

• Role-based authentication

  • Two user roles: Faculty and Student

• Student functionalities

  • View available courses
  • Register for courses

• Faculty functionalities

  • Create and manage courses
  • Edit course details
  • Delete courses

This setup simulated a basic but realistic multi-role workflow — making it a suitable sandbox to apply and validate MVCS principles in Django.

The full source code of project can be found on GitHub here.

A High-level workflow of the system is represented visually in the Figure below

How I Implemented MVCS in Django

To implement MVCS architecture in the Course Management System, I structured the codebase to clearly separate each responsibility layer by defining dedicated folders:

• models/ - Contains Django models representing the database schema.

• infrastructure/ - Acts as a repository layer that abstracts direct database interactions, providing robust error handling for database-level exceptions.

• services/ - Contains the business logic layer responsible for handling core operations and use cases.

• views/ - Contains controllers handling HTTP requests and delegating work to services.

• urls/ - Contains app-specific URL routing.

To understand the dataflow further let's see some code snippet examples from the project

Model Layer (registrationmanagement/models/course_models.py)

import uuid

from django.db import models


class Course(models.Model):
    course_id = models.UUIDField(
        primary_key=True, editable=False, unique=True, default=uuid.uuid4
    )
    course_name = models.CharField(max_length=100)
    course_description = models.CharField(max_length=500)
    course_code = models.CharField(max_length=20, unique=True)
    primary_instructor = models.ForeignKey(
        "registrationmanagement.Faculty", on_delete=models.CASCADE
    )
    instructors = models.ManyToManyField(
        "registrationmanagement.Faculty", related_name="instructors"
    )

    def __str__(self):
        string_representation = f"{self.course_name} - ({self.course_code})"
        return string_representation

    class Meta:
        app_label = "registrationmanagement"

Infrastructure Layer (registrationmanagement/infrastructure/course_repo.py)

from core.utils.types import Error
from registrationmanagement.models import Course
from registrationmanagement.utils.types import (
    CourseQuerySetType,
    CourseRegistrationQuerySetType,
)


class CourseRepo:
    @staticmethod
    def get_courses_exlcuding_enrolled_courses(
        enrolled_courses: CourseRegistrationQuerySetType,
    ) -> tuple[CourseQuerySetType, Error]:
        try:
            courses = Course.objects.exclude(
                course_id__in=enrolled_courses.values_list("course_id", flat=True)
            )
            return courses, None
        except Exception as e:
            return None, str(e)

    @staticmethod
    def get_course_by_id(course_id: int) -> tuple[Course, Error]:
        try:
            course = Course.objects.get(course_id=course_id)
            return course, None
        except Exception as e:
            return None, str(e)

    @staticmethod
    def get_courses_by_faculty(user) -> tuple[CourseQuerySetType, Error]:
        try:
            courses = Course.objects.filter(primary_instructor__user=user)
            return courses, None
        except Exception as e:
            return None, str(e)

    @staticmethod
    def create_course(course_data) -> tuple[Course, Error]:
        try:
            course = Course.objects.create(**course_data)
            course.instructors.add(course.primary_instructor)
            course.save()
            return course, None
        except Exception as e:
            return None, str(e)

Service Layer(registrationmanagement/services/course_service.py)

from core.utils.types import Error
from registrationmanagement.infrastructure import CourseRepo, FacultyRepo
from registrationmanagement.utils.types import (
    CourseQuerySetType,
    CourseRegistrationQuerySetType,
    CourseType,
)


class CourseService:
    @staticmethod
    def fetch_courses(
        enrolled_courses: CourseRegistrationQuerySetType,
    ) -> tuple[CourseQuerySetType, Error]:
        courses, error = CourseRepo.get_courses_exlcuding_enrolled_courses(
            enrolled_courses
        )
        if error:
            return None, error
        return courses, error

    @staticmethod
    def fetch_courses_by_faculty(user) -> tuple[CourseQuerySetType, Error]:
        courses, error = CourseRepo.get_courses_by_faculty(user)
        if error:
            return None, error
        return courses, error

    @staticmethod
    def create_course(request, course_data) -> tuple[CourseType, Error]:
        faculty, error = FacultyRepo.get_faculty_by_user(request.user)
        if error:
            return None, error
        course_data["primary_instructor"] = faculty
        course, error = CourseRepo.create_course(course_data)
        if error:
            return None, error
        return course, None

Note:

In this architecture, the assumption is that service layers should not contain exception handling (try-except blocks).

Errors should be handled either in the infrastructure layer or bubbled up for the controller to manage.

This keeps the service layer clean and focused on business logic, avoiding unnecessary coupling with error-handling responsibilities.

View Layer(registrationmanagement/views/course_views.py)

from django.contrib import messages
from django.contrib.auth.decorators import login_required
from django.shortcuts import redirect, render

from registrationmanagement.forms import CourseCreationForm
from registrationmanagement.services import CourseService
from registrationmanagement.utils import CourseResponseMessage


@login_required
def course_creation(request):
    if request.user.role != "Faculty":
        return redirect("home")
    if request.method == "POST":
        course_form = CourseCreationForm(request.POST)
        if course_form.is_valid():
            _, error = CourseService.create_course(request, course_form.cleaned_data)
            if error:
                messages.error(request, error)
                return render(
                    request,
                    "registrationmanagement/course_creation.html",
                    {"course_form": course_form},
                )
            messages.success(
                request, CourseResponseMessage.COURSE_CREATED_SUCCESSFULLY.value
            )
            return redirect("home")
        return render(
            request,
            "registrationmanagement/course_creation.html",
            {"course_form": course_form},
        )
    return render(
        request,
        "registrationmanagement/course_creation.html",
        {"course_form": CourseCreationForm()},
    )

This view is now lightweight, just handling request parsing and responses — no business logic here.

The data flow is illustrated in the diagram below.

Why MVCS Makes Sense

MVCS in Django isn't about breaking the framework's philosophy it’s about refining it. Django is flexible, and MVCS leverages that to give your apps:

• Better separation of concerns
• Easier unit testing and refactoring
• Cleaner and more maintainable codebases
• A structure that scales gracefully

You don’t need a giant app to try this out. Even for side projects, MVCS helps build with clarity and intention.

Final thoughts

If you’ve ever felt like your Django views were doing too much or your logic was scattered, MVCS might be the architecture you didn’t know you needed. It’s a small change in mindset — but a huge upgrade in maintainability.

Have thoughts or want to discuss how you structure your Django apps? Feel free to drop a comment!