Generate a Unique String in Python/Django

Question

What I want is to generate a string(key) of size 5 for my users on my website. More like a BBM PIN.

The key will contain numbers and uppercase English letters:

Answer 1

size = 5
''.join(random.choice(string.letters[26:] + string.digits) for in range(size))

this will generate some short code, but they can be duplicated. so check if they are unique in your database before saving.

def generate(size=5):
    code = ''.join(random.choice(string.letters[26:] + string.digits) for in range(size))
    if check_if_duplicate(code):
        return generate(size=5)
    return code

or using django unique constrain, and handle exceptions.