Understanding When to Use Django Signals or Override the Save Method

Django Signals vs. Overriding Save Method: Understanding the Right Choice

Overriding the save() method:

This involves modifying the built-in save() method within your model class to define custom logic before or after saving the instance. Here's an example:

class MyModel(models.Model):
    name = models.CharField(max_length=200)

    def save(self, *args, **kwargs):
        # Custom logic before saving
        self.name = self.name.upper()  # Make the name uppercase

        super().save(*args, **kwargs)  # Call the original save method

        # Custom logic after saving
        print(f"Model '{self.name}' saved successfully!")

Using Django signals:

Django provides a built-in mechanism called signals that allow you to connect functions (receivers) to specific events in your application. This promotes decoupling and makes your code more reusable and maintainable.

Here's an example using the post_save signal to send a notification after saving:

from django.db.models.signals import post_save
from django.dispatch import receiver

@receiver(post_save, sender=MyModel)
def send_notification(sender, instance, created, **kwargs):
    if created:  # Only send notification for newly created instances
        # Send notification logic using email or any other method

# Register the signal in your app's `ready()` function:
def ready(self):
    post_save.connect(send_notification, sender=MyModel)

Choosing the Right Approach:

  • Use save() override:

    • When the logic is specific to the model and tightly coupled with the saving process.
    • For simple tasks like data manipulation before saving.
  • Use signals:

    • When the action needs to be decoupled from the model and potentially apply to multiple models.
    • When the action needs to happen at specific points in the saving process (pre-save, post-save, etc.).
    • When the action involves interacting with other models or external systems.

Related Issues:

  • Circular dependencies: Overriding save() can lead to circular dependencies if different models reference each other's logic. Signals avoid this issue.
  • Testability: Signals are generally easier to test in isolation compared to code within the save() method.


Both Django signals and overriding save() methods offer effective ways to extend model functionalities. Understanding their strengths and weaknesses allows you to choose the most appropriate approach for your specific needs, promoting clean, maintainable, and decoupled code.

python django django-models

Random Fun with Python Lists: How to Grab a Surprise Element

Methods for Random Selection:Python offers several ways to achieve random selection from a list, depending on your specific needs:...

Python String Reversal: Unveiling Slicing and the reversed() Method

Using Slicing:This is the most concise and Pythonic way to reverse a string. Python strings are sequences, which means they can be accessed by index...

Efficient Techniques to Reorganize Columns in Python DataFrames (pandas)

Understanding DataFrames and Columns:A DataFrame in pandas is a two-dimensional data structure similar to a spreadsheet...

Collisions in the Arrayverse: Understanding the Trade-offs of Hashing Techniques

Understanding Hashing Arrays:Hashing involves converting an object (the array) into a unique, fixed-length value (the hash) that acts as a fingerprint...

Unlocking Performance Insights: Calculating Accuracy per Epoch in PyTorch

Understanding Accuracy CalculationEpoch: One complete pass through the entire training dataset.Accuracy: The percentage of predictions your model makes that are correct compared to the actual labels...

python django models

Why Django's model.save() Doesn't Call full_clean() and What You Can Do About It

The Reason Behind the SeparationThere are two primary reasons why Django separates save() and full_clean():Flexibility: Separating these methods allows for more granular control over the validation process