Separation of business logic and data access in django

python

best-practices

mvc-patterns

django-features

byNikita Barsukov·Oct 10, 2024

Employ the service layer for clean separation in Django: encapsulate business logic in services (services.py) and keep models (models.py) focused on data access. This promotes code reusability and testability.

# services.py - encapsulate business processes
def update_item_stock(item_id, new_stock):
    # Just like in real life, we get our item before we can update it 
    item = Item.objects.get(pk=item_id)
    item.stock = new_stock
    item.save()
    # Just like your favorite shopping site, we return an updated item 
    return item

# views.py - interact with business logic, not data models
from .services import update_item_stock

def item_stock_update_view(request, item_id, new_stock):
    # Don't call us, we'll call you - update_item_stock is on the job!
    update_item_stock(item_id, new_stock)
    # respond accordingly

This distinct separation clarifies intent, reduces coupling, and simplifies future modifications.

Understanding data and domain models

To keep your Django project organized and tidy, you must understand the difference between data models and domain models. The former represents your database schema, while the latter contains the business rules powering your app.

Incorporating a service layer

A service layer ensures that data access and business logic are two peas in different pods. It's essentially a set of functional modules separating views and models. This greatly enhances the abstraction of your code and simplifies complex business processes.

Using command and query distinction

The principle of Command Query Responsibility Segregation (CQRS) is an invaluable strategy for organizing Django applications. Using this technique, you separate actions (commands) that change the system's state from those that retrieve (query) the state. Just like in a symphony orchestra!

Proxy models and query models to the rescue

Proxy models and query models are your super-tools for specific use cases. To add or alter features of existing models, use Proxy models. For highly specific data slices meeting only one use case, query models come in handy.

Keeping your code lean and mean

Ensure your code stays clean by conforming to good coding practices. Keep logic well encapsulated and well named. Always remember: "Clean code is joyful code, a fearful programmer creates nothing!".

Django features and patterns

Utilize the power of Django's features and patterns for easier scalability and improved functionality of your apps. Use custom managers, middleware, management commands, and templates to offer a seamless experience.

Developing with performance in mind

Streamlining models

Break down larger models into smaller, single-task focused ones. This approach adheres to the Single Responsibility Principle, leading to cleaner, more maintainable code.

Django's built-in features for fast development

Get the most out of Django's in-built features like ModelForm and User class to craft powerful applications at lightning speed.

Learning from the community

Take inspiration from existing Django projects within the community. Understand how they've structured their applications and gain insights into designing MVC-compliant applications.

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