Google form url point to last updated answer - google-apps-script

Question

I have created a Google form with a Google spreadsheet associated to it that can be accessed (using the form URL) by each recipient I am sending it to. Right now the URL isn't unique to each recipient. The recipient can access the form then submit it. Upon submit, I am generating an edit URL via the GetEditResponse() function available in the Google FormResponse Class. The recipient can then edit their response using the edit url I provide them once they submit the form.
Here is my Google App Script code:
function myFunction() {
assignEditUrls();
}
function assignEditUrls() {
var form = FormApp.openById('formId');
//enter form ID here
var sheet = SpreadsheetApp.getActiveSpreadsheet().getSheetByName('Form Responses');
//Change the sheet name as appropriate
var data = sheet.getDataRange().getValues();
var urlCol = 5; // column number where URL's should be populated; A = 1, B = 2 etc
var responses = form.getResponses();
var timestamps = [], urls = [], resultUrls = [];
for (var i = 0; i < responses.length; i++) {
timestamps.push(responses[i].getTimestamp().setMilliseconds(0));
urls.push(shortenUrl(responses[i].getEditResponseUrl()));
}
for (var j = 1; j < data.length; j++) {
resultUrls.push([data[j][0]?urls[timestamps.indexOf(data[j][0].setMilliseconds(0))]:'']);
}
sheet.getRange(2, urlCol, resultUrls.length).setValues(resultUrls);
}
function shortenUrl(longUrl) {
// google url shortener api key
var key = "apiKey";
var serviceUrl="https://www.googleapis.com/urlshortener/v1/url?key="+key;
var options={
muteHttpExceptions:true,
method:"post",
contentType: "application/json",
payload : JSON.stringify({'longUrl': longUrl })
};
var response=UrlFetchApp.fetch(serviceUrl, options);
if(response.getResponseCode() == 200) {
var content = JSON.parse(response.getContentText());
if ( (content != null) && (content["id"] != null) )
return content["id"];
}
return longUrl;
}
You can also view the Spreadsheet associated with the form.
The problem with this model is that the recipients need to get back an edited URL in order to edit their response at a later time. Instead I want them to keep the same URL I originally provided them with and each time they come back to that URL I should identify which recipient it is and redirect them with the last updated URL.
For that scenario to happen I would need to:
1. Create a unique URL (identifier) for each recipient.
2. The same URL should point to the last updated URL (Form) so that they can always use the same URL originally provided (backend process).
Is this possible to achieve using Google's available tools? If it is, how can I create a unique url to identify which recipient responded to the form?

Answer 1

Staying within the confines of Google Apps Script, you cannot provide a redirection to a Google Form.
Here are two ideas off the top of my head...
If you're willing to use another service to handle the redirection, you could have it do the redirection for you. (I'm not recommending any, just saying it's an option.)
You could write a Google Apps Script web service that would present a mock-up of your real form. Users would have a unique URL to pass their unique identifier as a HTTP query parameter; heck, you could use goo.gl to produce a short URL for each of them as you do now. Based on the identifier, pre-fill the fake form with their last results. Upon commit, your web service can submit the form programmatically.

Answer 2

Create a unique URL (identifier) for each recipient.
Creating a separate Google Form for each person will give you this.
The same URL should point to the last updated URL
Assuming your go with creating a separate Form for each user, try placing the edit URL back into each Form's description or 1st page some where after submission of the 1st response. You'd have to make it clear that they have to click on that link going forward. There isn't a setting to automatically re-direct original Google Form URLs to their corresponding Edit Response ones AFAIK, if that's what you are asking for.