Handling Django's DoesNotExist Exceptions with Custom Model Representations

Your approach to overriding the __repr__ method in a base model class is a good solution to the infinite recursion issue that affected the original Django enhancement for nicer DoesNotExist errors.

Understanding the Issue

The problem occurs because Django's default model __repr__ implementation calls __str__, and in certain scenarios (particularly when dealing with related objects that might not exist), this can lead to infinite recursion when trying to display error messages for DoesNotExist exceptions.

Your Solution

Your implementation:

PYTHONCopied
def __repr__(self):
    return f'<{self.__class__.__name__} pk={self.pk}>'

This is a clean approach because:

1. It avoids calling __str__, preventing the potential recursion
2. It provides useful information (model class name and primary key)
3. It follows the standard Python convention for object representations

Implementation in a Base Model Class

You can implement this in a common base class for all your models:

PYTHONCopied
from django.db import models

class BaseModel(models.Model):
    def __repr__(self):
        return f'<{self.__class__.__name__} pk={self.pk}>'
    
    class Meta:
        abstract = True

Then have your models inherit from this base class:

PYTHONCopied
class MyModel(BaseModel):
    name = models.CharField(max_length=100)
    # other fields...

Handling DoesNotExist Exceptions

With this approach, when you catch ObjectDoesNotExist exceptions, the error messages will be more readable and won't cause recursion issues:

PYTHONCopied
from django.core.exceptions import ObjectDoesNotExist

try:
    obj = MyModel.objects.get(pk=1)
except ObjectDoesNotExist:
    # This will now display a cleaner error message
    # without risk of infinite recursion
    pass

This is a good example of overriding predefined model methods to enhance Django's behavior while avoiding potential issues.