how to avoid duplicate records in django code example

Example 1: how to avoid inserting duplicate records in orm django

if not table.objects.filter(column1=values).exists():
    # Insert new data here
    table.objects.create(column1=v1, column2=v2)

Example 2: django prevent duplicate entries

for instance in Stock.objects.all():
			if instance.category == category:
				raise forms.ValidationError(str(category) + ' is already created')
		return category