Django REST Framework includes a default mechanism for catching errors and formatting responses. Developers can override this behavior by defining a dedicated error processing function.

Logging Infrastructure Setup

Before handling exceptions, configure the logging pipeline in settings.py to capture runtime faults effectively.

# settings.py
import os
from pathlib import Path

BASE_DIR = Path(__file__).resolve().parent.parent

LOGGING = {
    'version': 1,
    'disable_existing_loggers': False,
    'formatters': {
        'detailed': {
            'format': '%(asctime)s [%(levelname)s] %(module)s:%(lineno)d - %(message)s'
        },
        'compact': {
            'format': '[%(levelname)s] %(module)s:%(lineno)d - %(message)s'
        }
    },
    'filters': {
        'debug_mode_only': {
            '()': 'django.utils.log.RequireDebugTrue'
        }
    },
    'handlers': {
        'terminal': {
            'level': 'INFO',
            'class': 'logging.StreamHandler',
            'formatter': 'compact',
            'filters': ['debug_mode_only']
        },
        'rotating_file': {
            'level': 'INFO',
            'class': 'logging.handlers.RotatingFileHandler',
            'filename': os.path.join(BASE_DIR, 'logs/runtime_events.log'),
            'maxBytes': 314572800,
            'backupCount': 10,
            'formatter': 'detailed'
        }
    },
    'loggers': {
        'django.core': {
            'handlers': ['terminal', 'rotating_file'],
            'propagate': True,
            'level': 'INFO'
        }
    }
}

Implementing the Fault Processor

Create a module such as project_api/handlers.py to house the custom logic. The function receives the raised error and the execution context.

# project_api/handlers.py
from rest_framework.views import exception_handler as base_error_processor
import logging
from django.db import DatabaseError
from redis.exceptions import RedisError
from rest_framework.response import Response
from rest_framework import status

error_tracker = logging.getLogger('django.core')

def api_fault_handler(error, execution_context):
    """
    Intercepts unhandled exceptions and standardizes the API response.
    """
    standard_response = base_error_processor(error, execution_context)

    # DRF only handles validation, authentication, and routing errors by default.
    # If standard_response is None, it indicates an unhandled system-level fault.
    if standard_response is None:
        current_view = execution_context.get('view')
        
        # Intercept database or cache layer failures
        if isinstance(error, (DatabaseError, RedisError)):
            error_tracker.error('Critical fault in [%s]: %s', current_view, str(error))
            standard_response = Response(
                {"detail": "Service temporarily unavailable due to backend failure"},
                status=status.HTTP_507_INSUFFICIENT_STORAGE
            )
            
    return standard_response

Registration in Configuration

Link the custom handler to the framework through the project settings.

REST_FRAMEWORK = {
    'EXCEPTION_HANDLER': 'project_api.handlers.api_fault_handler'
}

Testing with a Simulated Failure

A ViewSet can trigger the handler intentionally to verify the pipeline.

from rest_framework import mixins, viewsets
from rest_framework.decorators import action
from rest_framework.response import Response
from django.db import DatabaseError
from .models import ProductRecord
from .serializers import ProductSerializer

class ProductViewSet(mixins.ListModelMixin, viewsets.GenericViewSet):
    queryset = ProductRecord.objects.all()
    serializer_class = ProductSerializer

    @action(detail=False, methods=['GET'], url_path='test-fault')
    def trigger_system_error(self, request):
        raise DatabaseError('Mocked database connection timeout')

Framwork-Built Error Types

The framework natively recognizes and transforms several exception classes into HTTP responses:

Exception Class	Description
APIException	Base class for all framework errors
ParseError	Malformed request payload
AuthenticationFailed	Invalid credentials provided
NotAuthenticated	Missing authentication token
PermissionDenied	Valid credentials but insufficient access
NotFound	Resource does not exist
MethodNotAllowed	HTTP verb not supported by endpoint
NotAcceptable	Requested content type cannot be served
Throttled	Request rate limit exceeded
ValidationError	Input data fails serializer rules

Intercepting Missing Object Queries

ORM lookups often raise DoesNotExist exceptions. These can be captured and converted into a 404 Not Found response before reaching the default handler.

# project_api/handlers.py (Alternative implementation)
from django.core.exceptions import ObjectDoesNotExist
from rest_framework.exceptions import NotFound
from rest_framework.views import exception_handler as default_handler
import logging

query_logger = logging.getLogger(__name__)

def handle_missing_resources(error, ctx):
    query_logger.exception('Caught unexpected query exception')
    
    # Transform ORM missing object into DRF 404
    if isinstance(error, ObjectDoesNotExist):
        mapped_error = NotFound(detail='Requested record could not be located')
        return default_handler(mapped_error, ctx)
        
    return default_handler(error, ctx)

Update the EXCEPTION_HANDLER path to point to handle_missing_resources if adopting this specific behavior.