Error when use function document()

Question

In my interface, I user function document. 
 if(
 document(tofolder(local!documentId), "size") > 0,
 true,
 false
 )

Naresh · Answer

Hi, 
 Looks like the provided document id have null value (local!documentId). You can add null check condition to solve this issue. See below sample code 
 
 if(
 and(
 a!isNotNullOrEmpty(local!documentId),
 document(tofolder(local!documentId), "size") > 0
 ),
 true,
 false
)

Deepak gupta · Answer

In document function, you have to provide documentId not the folder id. 
 if(
 document(todocument(ri!documentId), "size") > 0,
 true,
 false
)

Ujjwal Rathore · Answer

Create a rule with the below to check whether the document is valid or not. 
 a!localVariables(
 local!document: 46,/*ID for any document */
 local!contentData: if(
 isnull(local!document),
 null,
 getcontentobjectdetailsbyid(local!document)
 ),
 if(
 isnull(local!document),
 false(),
 and(
 not(
 exact(
 local!contentData,
 "No object with this ID has been found"
 )
 ),
 find("Type: Document", local!contentData)
 )
 )
)

Mike Schmitt · Answer

Newly-uploaded documents exist in a "special" system directory in Appian, and are moved to their eventual "target" destination upon Form Submission. While still in that "special" directory, the document() function does not work on them, but they *do* have a valid Doc ID and certain (limited) functions still work on them - such as the "content object details by id" rule. 
 this is a useful capability to know, because it can be used on-form to judge whether a particular document is previously uploaded or brand new, and control other functionality that depends on this.