Menu
I'm looking for a data structure pattern for storing recurring events, but everything I came up with would result in a high number of special case handling or user input and data retrieval are overly complex. (I get the distinct feeling, that I haven't understand the problem domain well enough to do this.)
How can I store Outlook-style recurring events?
786
Add a recurrence domain to the database that supports a number of different values, including “daily”, “weekly”, and “monthly”. Add a recurrence column to the events table that identify how an event recurs. Add a recurrence_dates table that contains a pre-generated list of recurrences for a given date.
A Recurring Event is any event that happens more than once.
Set up a new repeating eventOn your computer, open Google Calendar. Add the event title and any other details. Choose how often you want the event to repeat, and when you want the event that repeats to end. At the top right, click Save.
There are various papers describing data structures and algorithms for this use case. In addition you can see the code or descriptions of open source implementation of crontab and of Quartz (Java) or Quartz.NET (.NET).
This is one such paper
http://portal.acm.org/citation.cfm?id=359763.359801&coll=ACM&dl=ACM&CFID=63647367&CFTOKEN=55814330
For example, cron stores the information like this (* means every, so a * under month means every month)
.---------------- minute (0 - 59) | .------------- hour (0 - 23) | | .---------- day of month (1 - 31) | | | .------- month (1 - 12) OR jan,feb,mar,apr ... | | | | .---- day of week (0 - 6) (Sunday=0 or 7) OR sun,mon,tue,wed,thu,fri,sat | | | | | * * * * * There are several special entries, most of which are just shortcuts, that can be used instead of specifying the full cron entry: Entry Description Equivalent To @reboot Run once, at startup. None @yearly Run once a year 0 0 1 1 * @annually (same as @yearly) 0 0 1 1 * @monthly Run once a month 0 0 1 * * @weekly Run once a week 0 0 * * 0 @daily Run once a day 0 0 * * * @midnight (same as @daily) 0 0 * * * @hourly Run once an hour 0 * * * *
176
Support the standard iCalendar Event types
The IETF put some thought into this when they created the Internet Calendaring and Scheduling Core Object Specification, better known as iCalendar.
The specification includes event recurrence.
As an added bonus, your database will be amenable to sharing data with other iCalendar compatible data sources such as Google and Apple calendars.
https://www.rfc-editor.org/rfc/rfc5545
45
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
