পার্ট ২: অ্যাপ ডেভেলপমেন্ট বেস সেটআপ

python manage.py startapp common

mkdir apps
mv common apps/

INSTALLED_APPS = [
    ...
    'apps.common',
]

apps/common/
├── __init__.py
├── exceptions.py   # কাস্টম exceptions
├── utilities.py    # শেয়ার্ড utility functions
├── validators.py   # কাস্টম validators

class CustomAPIException(Exception):
    def __init__(self, message, code=400):
        self.message = message
        self.code = code
        super().__init__(self.message)

def generate_unique_id():
    import uuid
    return str(uuid.uuid4())

def validate_positive(value):
    if value < 0:
        raise ValueError("This field must be a positive value.")

python manage.py startapp core

mv core apps/

INSTALLED_APPS = [
    ...
    'apps.core',
]

apps/core/
├── __init__.py
├── admin.py
├── apps.py
├── models.py
├── urls.py           # অ্যাপ-স্পেসিফিক URL
├── views.py
├── templates/
│   └── core/
│       └── home.html

from django.urls import path
from . import views

urlpatterns = [
    path('', views.home, name='home'),
]

from django.shortcuts import render

def home(request):
    return render(request, 'core/home.html', {'title': 'Home Page'})

from django.contrib import admin
from django.urls import path, include

urlpatterns = [
    path('admin/', admin.site.urls),
    path('', include('apps.core.urls')),  # Core অ্যাপের URL
]

{% extends "base.html" %}

{% block title %}
Home Page
{% endblock %}

{% block content %}
<h1>Welcome to the Home Page</h1>
<p>This is the main page of your application.</p>
{% endblock %}

STATICFILES_DIRS = [BASE_DIR / 'static']

TEMPLATES[0]['DIRS'] = [BASE_DIR / 'templates']

project/
├── apps/
│   ├── common/
│   │   ├── __init__.py
│   │   ├── exceptions.py
│   │   ├── utilities.py
│   │   └── validators.py
│   ├── core/
│   │   ├── __init__.py
│   │   ├── admin.py
│   │   ├── apps.py
│   │   ├── models.py
│   │   ├── urls.py
│   │   ├── views.py
│   │   └── templates/
│   │       └── core/
│   │           └── home.html
├── config/
│   ├── settings/
│   │   ├── __init__.py
│   │   ├── base.py
│   │   ├── development.py
│   │   └── production.py
│   ├── urls.py
│   ├── wsgi.py
│   ├── asgi.py
├── static/
├── templates/
│   └── base.html
├── media/
├── manage.py
├── .env
├── requirements.txt
└── venv/

python manage.py runserver