How can I overwrite the old file with app script when I save the file? - google-apps-script

Question

I have a few pages in google sheet. I'm getting the PDF output of Sheet2 from these pages with the code below. When the pdf prints out, it deletes the old pdf printout and creates a new one instead. When this happens, the links of the pdfs are changed. I don't want the link of the pdf to change. When it creates the new pdf I want it to overwrite the old one. How do I do this?
function checkSheet() {
var sheetName = "Sheet2";
var folderID = "folderid"; // Folder id to save in a folder.
var pdfName = "Catalog";
var sourceSpreadsheet = SpreadsheetApp.getActive();
var sourceSheet = sourceSpreadsheet.getSheetByName(sheetName);
var folder = DriveApp.getFolderById(folderID);
//Copy whole spreadsheet
var destSpreadsheet = SpreadsheetApp.open(DriveApp.getFileById(sourceSpreadsheet.getId()).makeCopy("tmp_convert_to_pdf", folder))
//delete redundant sheets
var sheets = destSpreadsheet.getSheets();
for (i = 0; i < sheets.length; i++) {
if (sheets[i].getSheetName() != sheetName){
destSpreadsheet.deleteSheet(sheets[i]);
}
}
var destSheet = destSpreadsheet.getSheets()[0];
//repace cell values with text (to avoid broken references)
var sourceRange = sourceSheet.getRange(1,1,sourceSheet.getMaxRows(),sourceSheet.getMaxColumns());
var sourcevalues = sourceRange.getValues();
var destRange = destSheet.getRange(1, 1, destSheet.getMaxRows(), destSheet.getMaxColumns());
destRange.setValues(sourcevalues);
//delete old pdf
var files = DriveApp.getFolderById(folderID).getFiles();
while (files.hasNext()) {
var file = files.next();
if(file.getName() == "Catalog"){
DriveApp.getFileById(file.getId()).setTrashed(true);
}
}
//save to pdf
var theBlob = destSpreadsheet.getBlob().getAs('application/pdf').setName(pdfName);
var newFile = folder.createFile(theBlob);
//Delete the temporary sheet
DriveApp.getFileById(destSpreadsheet.getId()).setTrashed(true);
}

Answer 1

Your question contains a lot of unnecessary details. I believe it could be simplified to, "How can one update an existing PDF file on Google Drive?"
To do this, you have to enable Advanced Drive Service which has an update method that will replace an existing PDF file in Google Drive.
function replaceFile(theBlob,theFileId) {
var oldFile = DriveApp.getFileById(theFileId);
Drive.Files.update({title: oldFile.getName(),mimeType:
oldFile.getMimeType()}, theFileId, theBlob);
}
}