The filterByFormula field is how you “map” a URL to a record (or records). So if you don’t enter a filter by formula, then ever record in that table will be returned on each request.
For example, if I’m using Airpress Virtual Posts to display restaurants, I might do something like this:
example.com/restaurants/recXXXXXXXXXX
So the ‘URL Pattern to match’ would be:
^restaurant/(.*)
and the filterByFormula would be:
RECORD_ID() = ‘$1’
$1 equals whatever is ‘matched’ by the parenthesis in the ‘URL Pattern to match’.
I would recommend using a custom column called ‘Slug’ or ‘Post Name’ in Airtable. So for a restaurant named, “Joe’s Dingy Tavern” you would probably want the slug/postname to be, “joes-dingy-tavern”.
In that case, your filterByFormula would be:
{Slug} = ‘$1’
Then you could access this Virtual Post by visiting:
example.com/restaurants/joes-dingy-tavern
Here’s a helpful resource for experimenting with regular expressions:
http://www.phpliveregex.com/p/iFW
Let’s move support discussions to the Wordpress support forum:
https://wordpress.org/support/plugin/airpress