Adding a default Variation when creating a new Item

[Ahmed Khairy]

I have created this code for defining a default everytime I create a new product, 

It is working fine and whenever I create a new Item a new variable (size) is create 

I want to check whether this code is correct or not as I have had help from someone and I think we could have created an easier way for it 

class Item(models.Model):

    title = models.CharField(max_length=100)

    price = models.DecimalField(decimal_places=2, max_digits=100)

    category = models.CharField(choices=CATEGORY_CHOICES, max_length=2)

    label = models.CharField(choices=LABEL_CHOICES, max_length=1)

    slug = models.SlugField(unique=True)

    timestamp = models.DateTimeField(default=timezone.now)

    active = models.BooleanField(default=True)

    def __str__(self):

        return self.title

class VariationManager(models.Manager):

    def all(self):

        return super(VariationManager, self).filter(active=True)

    def sizes(self):

        return self.all().filter(category='size')

    def colors(self):

        return self.all().filter(category='color')

VAR_CATEGORIES = (

    ('size', 'size',),

    ('color', 'color',),

    ('package', 'package'),

)

class Variation(models.Model):

    item = models.ForeignKey(Item, on_delete=models.CASCADE)

    category = models.CharField(

        max_length=120, choices=VAR_CATEGORIES, default='size')

    title = models.CharField(max_length=120)

    objects = VariationManager()

    updated = models.DateTimeField(auto_now_add=False, auto_now=True)

    active = models.BooleanField(default=True)

    def __str__(self):

        return self.title

@receiver(post_save, sender=Item)

def add_default_Variant(sender, instance, **kwargs):

    small_size = Variation.objects.create(

        item=instance, category='size', title='Small')

    medium_size = Variation.objects.create(

        item=instance, category='size', title='Medium')

    large_size = Variation.objects.create(

        item=instance, category='size', title='Large')

@receiver(post_save, sender=Item)

def add_default_Variant(sender, instance, **kwargs):

    variant, created = Variation.objects.get_or_create(

        title="Small", item=instance)

    variant, created = Variation.objects.get_or_create(

        title="Medium", item=instance)

    variant, created = Variation.objects.get_or_create(

        title="Large", item=instance)

    print(f"default variant created : {variant}")