Google form file uploads: getting filenames - google-apps-script

Question

Other users posted similar questions here and here. I tried to replicate the answer but received it as undefined. My users are permitted to upload up to 5 files, I would like to append the filenames as responses in (up to) 5 columns in a spreadsheet.
I presume that I would be able to get the filenames once I have the URLs using the following example.
function driveFile(){
//e.values[1] is apparently the file URL
var url = "https://drive.google.com/open?id=1bVbNAnES33oY4gx8npdp51ZSMekQalk"
var id = url.split("=")[1];
var file = DriveApp.getFileById(id);
var fileName = file.getName();
}
I tried this as suggested in the other question and it returned undefined.
I also tried using 0 as it made sense to get the URLs of the different files as 0 to 4.
var file = e.values[1]
I also tried the example from the other question but to no avail. I'm also not sure if it would return the URLs concatenated or in an array.
var fileBlob = e.parameter.thefile;
I would appreciate any guidance in this topic. Get URL → Filenames for (up to) 5 files submitted via Google Forms.

Answer 1

Answer:
This can be done using an onSubmit() trigger attached to the Google Form.
Further information:
The problem you are encountering is that values is not a parameter of the event object obtained on form submission - this is why you are getting an undefined return.
Form responses are a little more complicated than this - they are objects with predefined methods and in order to obtain the information out of them you need to use the methods provided in the Apps Script Documentation for Forms.
Code:
function onSubmit(e) {
// Assumiung the question which asks for the file upload is question 1
// Change this to the correct question number:
var uploadQuestionNumber = 1;
var formResponses = e.response.getItemResponses();
var names = [];
var fileUploads = formResponses[uploadQuestionNumber - 1];
for (i = 0; i < fileuploads.getResponse().length; i++) {
name.push(DriveApp.getFileById(fileUploads.getResponse()[i]));
}
return name;
}
Variable name will return an array of all the file names of the uploaded files. You can then use this to put into a Sheet using SpreadsheetApp.
References:
Google Forms events - Form submit
Class FormResponse
Class ItemResponse
Class DriveApp
getFileById(id) method
Class File