Add a form field into the details bar on the entry edit screen and do something with the value I'd like to add a form field into the details bar on the entry edit page, so that when the entry gets submitted, the form field value gets passed into the data payload so that I can pick it up from the EVENT_BEFORE_SAVE event.
However, it does not seem to get passed into the data I can see in that hook. Is there any way to do this? I want to give the user an option to tick a box that on save of the entry, it sends some data off to a third party API.
Just take your value direct from the $_POST array.