DocumentApp openById invalid argument

Question

I am currently creating a program to open a txt file from a shared folder using the id. However, it outputted this error:

Invalid argument (line 14, file "main") line 14

var file2 = DocumentApp.openById("1CdUmn9aw2q94lx4Rbj7eYl0s8DAbt8Hq");

I have tried DriveApp to check if my string was wrong, but it was correct. Any suggestions on how to solve this?

user_11225291 · Answer

Explanation / Issue:

DocumentApp.openById('DOCUMENT_ID_GOES_HERE') requires a document ID but you are passing a file ID.

Solution:

Instead you want to try DriveApp.getFileById(id):

var file2 = DriveApp.getFileById(id)

and this will return an instance of the File class. Check the attached link for the available methods you can use with file2.