Is it possbile to check if the folder ID exists in Appian Document System?...

Hi cmtam, till now there is no such function that checks for the existence of the Appian Objects except for "User".

There has been a discussion regarding this topic last year that includes comments from myself :-) That might give you some ideas.
forum.appian.com/.../e-91772

I tested
=index(split(getcontentobjectdetailsbyid(57731), "Type: "), 2, "") = "Folder]"
and it works. But writing a plugin for that should be quite easy and a bit more reliable solution.

hi stefanh, thanks for the piece of code. That helps :-)

I just find out the same plugin and writing a rule :
=trim(extract(getcontentobjectdetailsbyid(ri!id), "Type:","]"))="Folder"

Thanks for your input

To have a stable solution for this, please write a plugin. If Appian rearranges the results of the getcontent...() function this would break the expression. This is the way I go for production.