FormResponse object missing when using DriveApp and Smartsheets Sync - google-apps-script

Question

My ultimate goal is to access the contents of a file uploaded via a Google Form from within a function triggered by formSubmit. I added some info in a comment to this question, but I think I need to update the question itself. When I deactivate the Smartsheets Sync add-on in the web form, this all works as expected. My theory is that the Smartsheets Sync add-on is not preserving the Event object in certain scenarios.
I began with:
function onFormSubmit (e) {
Logger.log (e);
}
I set up my trigger and tested a form submission, and in the log, I saw:
[<datetime>] {authMode=FULL, source=Form, response=FormResponse triggerUid=<id>}
as expected. I also explored the FormResponse object and verified that a valid Google Drive ID is in the response.
Next, I added a call to DriveApp.getFileById:
function onFormSubmit (e) {
Logger.log (e);
var responses = e.response.getItemResponses ();
var file = DriveApp.getFileById (responses [1].getResponse ());
Logger.log (file);
}
Resubmitting a form brings up a permission error with DriveApp. Not surprising, so I ran onFormSubmit directly from the script editor. It failed because it was invoked without an Event object, but it did invoke the dialog that allowed me to grant DriveApp permissions.
Now, when I submit a form, the Event object doesn't contain a FormResponse object. From the log:
[<datetime>] {authMode=FULL, source=Form, triggerUid=<id>}
So, does granting DriveApp permission somehow revoke permission to inspect the user's response? Alternatively, is there another way for me to use Google App Script to access a file uploaded via a Google Form?

Answer 1

The file ID is put into the file upload answer (response). The following code gets the answer to the file upload question, which is the file ID. Note that arrays are zero indexed, so the first question is at index zero. This code assumes that the file upload question is the very first question.
If this answers your question, you can mark it as correct by clicking the green arrow.
function onFormSubmit(e) {
var file,fileID,form,responseID,submittedResponse,uploadResponse;
responseID = e.response.getId();//The the ID of the current reponse
Logger.log('responseID: ' + responseID)
form = FormApp.getActiveForm();//Get the Form that this script is bound to
submittedResponse = form.getResponse(responseID);//Get the response that
//was just submitted
uploadResponse = submittedResponse.getItemResponses()[0];//This assumes
//that the very first question is the file upload
fileID = uploadResponse.getResponse();//Get the file ID of the file just uploaded
Logger.log('fileID: ' + fileID)
file = DriveApp.getFileById(fileID);//Get the file
Logger.log('file.getName(): ' + file.getName());//verify that this is
//the correct file - and that the code is working
}