Re: How many attempts to generate a unique ID?

[George Silva]

Do you need this identifier to be so short? If that's not a problem, why don't you use something tried and that's proven that will succeed: GUIDS (or UUIDs).

http://en.wikipedia.org/wiki/Globally_unique_identifier

http://docs.python.org/library/uuid.html

On Sun, Sep 9, 2012 at 8:10 PM, Anton Popovine <anton.p...@gmail.com> wrote:

Hi everyone! First time posting to this group!

I have a model Class where each row has a unique alphanumeric ID string like 'EX39H'.

This is the function I use to generate the code.

def gen_class_code():

  import string

  import random

  size = 5

  max_size = 16

  attempts = 1000

  chars = string.ascii_uppercase + string.digits 

  # lets try <attempts> times to generate unique id, else increase code length

  res = ""

  while (size <= max_size):

    for i in range(attempts):

      temp = ''.join(random.choice(chars) for i in range(size)) 

      if not Class.objects.filter(code=temp).exists():

        res = temp

        break

    if res : break

  return res 

How much would you set the attempts variable to and why?

Thanks in advance

Anton

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George R. C. Silva

Desenvolvimento em GIS
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[Anton Popovine]

Yes it needs to be short. This will be an invitation string most likely written on a chalk board for kids.

Also there was an error in my initial post : I forgot to increment size += 1 inside the while loop. Noticed right after posting.

thanks

[Tom Evans]

On Mon, Sep 10, 2012 at 12:31 AM, Anton Popovine
<anton.p...@gmail.com> wrote:
> Yes it needs to be short. This will be an invitation string most likely
> written on a chalk board for kids.
>
> Also there was an error in my initial post : I forgot to increment size += 1
> inside the while loop. Noticed right after posting.
>
> thanks
>

Have you considered just using a base 36 of the object id?

http://en.wikipedia.org/wiki/Base_36

Cheers

Tom