Hey @emilegutenkauf,
We’re super bummed you weren’t able to find a solution after our extensive work with you in support.
While Pie Calendar doesn’t natively offer a way to map its date fields to existing date fields, it’s 100% possible using something like WP All Import/Export to export your existing posts, then reimport the same posts to batch update the Pie Calendar fields using the data from your pre-existing fields.
We did advise on this briefly, but I’m sure you can understand how this kind of advanced setup isn’t something we can help with as part of our normal support.
Another solution would be to create a one-time script that fetches all posts that have your pre-existing date fields filled and copy their values over to the Pie Calendar fields. We have documentation on the existing Pie Calendar fields that would need to be populated in order for existing posts to show up on the calendar: https://docs.piecalendar.com/article/8-meta-fields
Finally, we have had multiple requests for some kind of option that would enable you to tell Pie Calendar to look at different meta fields for its date values instead of only the Pie Calendar fields. This is currently under investigation for inclusion in a future release and would also satisfy your need.
As you can see, there are a few ways you can currently accomplish what you need with the way Pie Calendar works today. If you’re not in a position to implement those options, I don’t believe that should be considered a failure on our part, but we’re excited to improve Pie Calendar in the future to better accommodate these kinds of scenarios.
Thanks for your valuable feedback and best of luck with whatever solution you decide to use!
