"setOwner" not a function error - App Script - google-apps-script

Question

new to Google Scripts and I've looked through other posts on Stack Overflow as well but couldn't find a good answer.
I'm using data collected in Google Sheets to search for a file in Google Drive and transfer ownership of the file. I have google form that my users fill out, once submitted using an add-on I create a file based on the data that was submitted on the form. Now with the script, I'm trying to go gather certain information from sheets such as name, email, and company name -
Sample data image here.
What I have thus far:
function myFunction() {
//Get google sheets
var spreadsheetId = '1WvIIoYdmuIB5BQ3KgSYOOIiEn-K_GTzCkb7rITzRFck';
//get certain values from sheets
var rangeName = 'MDP Form!C25:E';
var values = Sheets.Spreadsheets.Values.get(spreadsheetId, rangeName).values;
if (!values) {
Logger.log('No data found.');
} else {
Logger.log('Name, Email, Customer:');
for (var row = 0; row < values.length; row++) {
// Print columns C and E, which correspond to indices 0 and 4.
Logger.log('Name: %s, Email: %s, Company: %s', values[row][0], values[row][1], values[row][2]);
//Utilities.sleep(90000);
//Searching through google drive
var name = (values[row][0]);
var email = (values[row][1]);
Logger.log(email);
var company = (values[row][2]);
var fileName = ('Mutual Delivery Plan ' + company + ' - ' + name);
Logger.log(fileName);
//add a 1 minute delay
//Utilities.sleep(90000);
//search for target folder
var folder = DriveApp.getFolderById('1whvRupu9hWdyl2CqSF-KvdVj8VE6iiQu');
//search for file by name within folder
var mdpFile = folder.searchFiles(fileName);
//transfer ownership
mdpFile.setOwner(email);
}
}
}
Problem:
The script works for the most part except for the last line "setOwner" is not a function. I've tried creating a separate function for this, used some other suggestions on other posts but still cannot get this to work. If anyone has ideas around what might I be missing here or suggestions that would be super helpful. Thanks!

Answer 1

I believe your goal as follows.
You want to transfer the owner of the file when the file with fileName is found in folder.
For this, how about this answer?
Modification points:
Although you say The script works for the most part except for the last line "setOwner" is not a function., if your script in your question is the current script, how about the following modification?
In your script, fileName is 'Mutual Delivery Plan ' + company + ' - ' + name, and fileName is used with var mdpFile = folder.searchFiles(fileName);. In this case, an error occurs. Because params of searchFiles(params) is required to be the query string.
I think that in your case, it's "title='" + fileName + "'".
Also searchFiles(fileName) returns FileIterator. This has already mentioned by the existing answer. Because at Google Drive, the same filenames can be existing in the same folder and each files are managed by the unique ID. So here, it is required to be modified as follows.
I think that in your case, the following flow is useful.
Confirm whether the file is existing using hasNext().
When the file is existing and the owner is you, the owner of the file is changed to email.
When above points are reflected to your script, please modify as follows.
Modified script:
From:
var mdpFile = folder.searchFiles(fileName);
//transfer ownership
mdpFile.setOwner(email);
To:
var mdpFile = folder.searchFiles("title='" + fileName + "'");
while (mdpFile.hasNext()) {
var file = mdpFile.next();
if (file.getOwner().getEmail() == Session.getActiveUser().getEmail()) {
file.setOwner(email);
}
}
If you don't need to check whether the owner is you, please remove if (file.getOwner().getEmail() == Session.getActiveUser().getEmail()) {.
Note:
In this case, when the file with the filename of fileName is not existing in folder, the script in the if statement is not run. Please be careful this.
Also, when there are several files with the same filename in folder, the owner of those is changed to email.
References:
searchFiles(params)
FileIterator
hasNext()
next()
getActiveUser()

Answer 2

Folder.searchFiles() returns a fileIterator not a file. If it's the only file with that name then you can usually getaway with mdpFile.next();
File Iterator