Using the UrlShortener API in a custom Spreadsheet function - google-apps-script

Question

I would like to use an API (url shortener) with a public google Add-on.
For the moment my code returns:
Daily Limit for Unauthenticated Use Exceeded. Continued use requires signup.
Is this possible?
If yes, Do I need an authentification Token?
If yes, what key type should I choose?
How can I implement the authorisation for this kind of use?
Do I need to pay for it?
If no, How could other add-ons use external APIs
Thanks a lot for your answers,

Answer 1

EDIT: The OP pointed out in the comments that this is a custom function. Custom function run with limited authorization. A complete list of what is available is at:
https://developers.google.com/apps-script/guides/sheets/functions#using_apps_script_services
Below uses the REST API to get the shortened url. This will work with custom functions. You will just need to enable the URL Shortener API and generate a Server API Key. Use the IPs at the following link for your server api key:
https://developers.google.com/apps-script/guides/jdbc#setup_for_google_cloud_sql
/**
* Returns a shortened URL of the input.
*
* #param {string} longUrl The long URL to shorten.
* #return The shortened url.
* #customfunction
*/
function getShortUrl(longUrl) {
var payLoad = {"longUrl": longUrl};
var apiKey = PropertiesService.getScriptProperties().getProperty("ServerApiKey");
var url = "https://www.googleapis.com/urlshortener/v1/url?key="+ apiKey;
var options = { method:"POST",
contentType:"application/json",
payload:JSON.stringify(payLoad),
muteHttpExceptions:true};
var response = UrlFetchApp.fetch(url, options);
if(response.getResponseCode() != 200){throw new Error("Unable to shorten url");}
return JSON.parse(response).id;
}
Original Post
Here is a quick primer on using the UrlShortener advanced service. You will need to turn on the service and activate the Url Shortener api in the developers console. This will give you a quota of 1,000,000 requests per day for your add-on.
function myFunction() {
var url = UrlShortener.newUrl();
url.longUrl = "http://www.example.org";
var short = UrlShortener.Url.insert(url);
Logger.log(short);
//list all users shortened urls
Logger.log(UrlShortener.Url.list());
}