Thank you for your post.
In a calculation field, you can use the Count() function to count the number of entries in a Portal. If you perform a search for a particular date in a portal, the Count() will return the number of entries in that portal with that specific date. You can then summarize this across all records.
What do you do if you have a complex filter in place for your portal? Is there a better way to do this?
I use a 'found' field (which gets the found count) on the table occurrence that populates the portal. So on a layout based on ORGANISATION table occurrence, a portal showing Consultees within that organisation uses <<organisation_CONSULTEE::found>> to count the entries in the portal. As far as I can see, it gets an accurate count regardless of the complexity of the portal filter.
Does that work for you?