Django Unique Slug Generator

slugify.py

import random
import string
from django.utils.text import slugify

def random_string_generator(size=10, chars=string.ascii_lowercase + string.digits):
    return ''.join(random.choice(chars) for _ in range(size))

def unique_slug_generator(instance, new_slug=None):
    if new_slug is not None:
        slug = new_slug
    else:
        # We are using .lower() method for case insensitive
        # you can use instance.<fieldname> if you want to use another field
        str = replace_all(instance.name.lower())
        slug = slugify(str)

    Klass = instance.__class__
    qs_exists = Klass.objects.filter(slug=slug).exists()
    if qs_exists:
        new_slug = "{slug}-{randstr}".format(
                    slug=slug,
                    randstr=random_string_generator(size=4)
                )
        return unique_slug_generator(instance, new_slug=new_slug)
    return slug

def replace_all(text):
    rep = {
        'ı':'i',
        'ş':'s',
        'ü':'u',
        'ö':'o',
        'ğ':'g',
        'ç':'c'
    }
    for i, j in rep.items():
            text = text.replace(i, j)
    return text

usage.py

from django.dispatch import receiver
from django.db import models
from .slugify import unique_slug_generator

class TestModel(models.Model):
    name = models.CharField(max_length=150)
    slug = models.SlugField(unique=True, null=True, blank=True)

@receiver(models.signals.pre_save, sender=TestModel)
def auto_slug_generator(sender, instance, **kwargs):
    """
    Creates a slug if there is no slug.
    """
    if not instance.slug:
        instance.slug = unique_slug_generator(instance)