I'm not sure exactly what you're trying to accomplish.
In the Calendar API, there is an endpoint to Update a calendar event.
The first item there is calendar_event[context_code], which says it's "Context code of the course/group/user whose calendar this event should be added to." That makes it sound like it's the calendar something should belong to and by setting that value, you could change the calendar an event belongs to.
So, it sounds like if you do a Get a calendar event and do a Put with a different context_code, it should move it.
That's for a calendar event. For an assignment, it seems that it should always be associated with a course, so I'm not sure that it's changeable.
But you wrote that you looked in the API, so that's why I wrote I'm not quite sure what you're asking for. Maybe an example of what you're trying to do would help.
Disclaimer: I've not used the Calendar Events API, I'm just reading the docs, so I may be missing something there where it says one thing and doesn't actually do it.
I don't know of a way to change an event once you have created it. But if adjust your calendar settings before you start creating events, so that only the destination calendar shows, then whatever events you create will default to that calendar.
For example, let's say you're inputting office hours for ABC 123. Go into the calendar and turn off/hide all other courses and your personal calendar. Now, whenever you create an event, it will default to ABC 123.
I know this isn't exactly what you asked for, but maybe it will help someone in the future?
In most cases I would just advise that you create a new event in the other calendar and then delete the one in the first calendar. I've had to do that myself plenty of times.
(Meant to post this Aug 24th...)
Thank you so much for your input, I really appreciate it.
One of our faculty created a ton of "events" (for the entire term)
under her own calendar instead of the course calendar
so we were looking for an easier fix than deleting and re-creating.
The faculty has a better understanding of how to work with the Calendar now ; )
and I hope to revisit the Calendar API soon to try out your suggestion, James.
Thank you again,