I'm working on a Django project and encountering an issue with Django forms. Here's my current implementation:

# models.py
from django.db import models

class UserProfile(models.Model):
    user = models.OneToOneField(User, on_delete=models.CASCADE)
    bio = models.TextField()
    
# Signal handler
@receiver(post_save, sender=User)
def create_profile(sender, instance, created, **kwargs):
    if created:
        UserProfile.objects.create(user=instance)

The specific error I'm getting is: "django.db.utils.DataError: value too long for type character varying(100)"

I've already tried the following approaches:

• Checked Django documentation and Stack Overflow
• Verified my database schema and migrations
• Added debugging prints to trace the issue
• Tested with different data inputs

Environment details:

• Django version: 5.0.1
• Python version: 3.11.0
• Database: PostgreSQL 15
• Operating system: Windows 11

Has anyone encountered this before? Any guidance would be greatly appreciated!

This Django error typically occurs when you're trying to save a model instance that violates a unique constraint. Here's how to handle it properly:

from django.db import IntegrityError
from django.http import JsonResponse

try:
    user = User.objects.create(
        username=username,
        email=email
    )
except IntegrityError as e:
    if 'username' in str(e):
        return JsonResponse({'error': 'Username already exists'}, status=400)
    elif 'email' in str(e):
        return JsonResponse({'error': 'Email already exists'}, status=400)
    else:
        return JsonResponse({'error': 'Data integrity error'}, status=400)

Always use get_or_create() when you want to avoid duplicates:

user, created = User.objects.get_or_create(
    username=username,
    defaults={'email': email, 'first_name': first_name}
)

Python decorators with arguments require a three-level nested function. Here's the proper implementation:

import functools

# Decorator with arguments
def retry(max_attempts=3, delay=1):
    def decorator(func):
        @functools.wraps(func)  # Preserves function metadata
        def wrapper(*args, **kwargs):
            for attempt in range(max_attempts):
                try:
                    return func(*args, **kwargs)
                except Exception as e:
                    if attempt == max_attempts - 1:
                        raise e
                    time.sleep(delay)
        return wrapper
    return decorator

# Usage
@retry(max_attempts=5, delay=2)
def unreliable_function():
    # Function that might fail
    pass

Class-based decorator (alternative approach):

class Retry:
    def __init__(self, max_attempts=3, delay=1):
        self.max_attempts = max_attempts
        self.delay = delay
    
    def __call__(self, func):
        @functools.wraps(func)
        def wrapper(*args, **kwargs):
            for attempt in range(self.max_attempts):
                try:
                    return func(*args, **kwargs)
                except Exception as e:
                    if attempt == self.max_attempts - 1:
                        raise e
                    time.sleep(self.delay)
        return wrapper

# Usage
@Retry(max_attempts=5, delay=2)
def another_function():
    pass