Recurring events plan

Some events (such as user group meetings) are recurring - and even conferences can be seen as recurring as they happen every year

It would be nice to have a good way for the event owner to easily (and eventually automatically) add "the next" event in the series

The best way to do this would be to do it in a few steps, going onto the next one once the previous step is live and has been proven to be a popular feature that works as expected:

1. Have a "Create next event in series" button (and date field) that the event owner can use to duplicate the existing event. We perceive that one of the problems with regular events like user group meetings is that the approval delay is a problem for the organiser who often creates the event at short notice. Therefore, the "create next event in series" button should automatically approve the event and notify the joind.in administrators via email that the event has been created. Potentially, we may want to limit access to the "create next event in series" button to some event owners if there is any abuse?
2. Once that all works, it would be possible to use the previous two events to take an educated guess at when the next event may be, and pre-fill the date field - still allowing the event owner to manually change the date
3. Finally, for those event owners that want it (and possibly with moderation approval), have the events automatically created after the previous one has finished. This does have drawbacks though:
   • It's a good way to fill the database with junk events that weren't supposed to be there
   • We need to be completely sure that our intelligent guessing at the next event will get the next date in all cases, and is only wrong if the date changes as a one-off (eg. 2nd Tuesday instead of 1st Tuesday)
   • It will need use of cron, which isn't ideal

Notes:

• The idea of having a 'parent' event which has the recurring events as sub-events was considered but quickly discounted, because meta-comments can quickly become out-dated (comments about the venue are useless once the venue changes)
• Extra fields can be added to link the events together (next in series/previous in series), to add UI niceness to allow the visitor to easily browse between the events

Note that JOINDIN-234 is the issue that tracks any work on this plan.