Single position expiration

This is a plugin for pretix.

Allows single position to expire rather than the entire order

This plugin was made to solve the following scenario:

• Person $A$ places an order with item $I$, fully pays it. The order is in paid status

• The quota for $I$ becomes full, nobody can buy new $I$

• $A$ changes his order and adds a new item, HOWEVER he doesn’t pay the new cost, leaving the order in a pending status

• $A$’s order eventually expires (we have “Automatically expire unpaid orders” checked), so $I$ becomes again available

• Person $B$ arrives and buys $I$, quota is again full

• Now, even if $A$ finally pays for the extra item he recently added, he lost his right on $I$ even if he already paid for it.

Pretix team said (https://github.com/pretix/pretix/discussions/6130) that they’re not planning on properly implementing a solution for this usecase inside the main branch, so I made a simple plugin which:

• Every time an order becomes paid, marks each position as paid as well (it also saves the datetime of when this happens)

• When an order becomes expired:

  • If no position was marked as paid, it lets the order properly expire

  • Otherwise, it cancels every position which was NOT marked as paid, letting the order come back in the paid status

pip install flake8 isort black

black --check .
isort -c .
flake8 .

isort .
black .