New reference number format about ethics

[tymees]

A proposal for the new generate_ref_number:

def generate_ref_number():
    """
    Generates a reference number for a new(!) Proposal.
    NOTE: Use generate_revision_ref_number to create reference numbers for
    revisions! This function will always create a new ref.num. with version = 1
    :return: a reference number in the format {nr}-{vr}-{current_year}, 
    where nr is the number of Proposals created  in the current year excluding 
    revisions. Vr is the version of this proposal, this function will always return vr = 1.
    """
    from ..models import Proposal

    # Set default values
    current_year = datetime.now().year
    proposal_number = 1
    version_number = 1

    try:
        # We count all proposals for this year by selecting all proposals
        # with a reference number ending with the current year.
        num_proposals = Proposal.objects.filter(
            reference_number__endswith=current_year,
        ).count()
        proposal_number = num_proposals + 1
    except Proposal.DoesNotExist:
        # Should not happen(TM)
        pass

    return '{:02}-{:02}-{}'.format(
        proposal_number,
        version_number,
        current_year
    )

I've used a slightly different format than in my initial post: 'nr-vr-year'. This way the function doesn't have to be aware of the older formats to work, as they all have the year at the end.

[tymees]

Ended up with a slightly different implementation, it was easier to just check the created_on variable in the count query.

My implementation is in PR #90

There is a small bug however:
If you have Proposal A with an old ref-num and make a revision B with A as parent, everything is fine. (20-001-02)
If you then make a revision C with B as parent, everything is still fine. (20-001-03)
If you then make revision D with A as parent again, you will be given the ref number 20-002-02.

It's actually very hard to solve this, as the function that generates a new ref number from old ref numbers cannot be aware of any revisions with the new ref.num. (There is simply no easy way of finding those without the new proposal number used by the other revisions).

To be honest, I don't think it's a big problem. At least not big enough to justify the effort of fixing it

[JeltevanBoheemen]

Regarding the bug: I agree that it's minor enough to not warrant a complex fix.