Getting SubLabels in App Script Function from Gmail - google-apps-script

Question

Here the problem:
I have three different categories and I wanted to group them in a unique label with three sublables. Then, i want to pick those sublabels and run my script.
Here the actual situation in Gmail:
as is situation
I want to put all those labels under a main lable nesting them like this:
nested labels
Now, nesting lables in Gmail il very easy but the main problem is when you run a script based on nested labels. Here my function:
function getGmailEmails(){
var label = GmailApp.getUserLabelByName("UtentiSW");
var threads = label.getThreads();
for(var i = threads.length - 1; i >=0; i--){
var messages = threads[i].getMessages();
for (var j = 0; j <messages.length; j++){
var message = messages[j];
if (message.isUnread()){
extractDetails(message);
GmailApp.markMessageRead(message);
}
}
//threads[i].removeLabel(label); //delete the label after getting the message
}
}
If i try to create a nested label and pick it in the function using the name of the label as shown, does't work. It works only if i put the label in the root folder of gmail as per first picture.
Anyone can help? Thanks

Answer 1

Creating Labels and Sub Labels
Create Label before Sub Labels
function createLabelsAndSubLabel() {
const labels = ["Q1","Q1/1","Q1/2","Q1/3"]
labels.forEach(l => GmailApp.createLabel(l))
}
I've never tried it for more that 4 levels but if you want to extend it you can, just remember to create the labels before the sublabel or they all become separate labels and you have to go delete them and start all over again.
What it looks like in Gmail:
Sorry my back is an image
Listing all of your labels in a Spreadsheet
function listAllLabels() {
let labels = JSON.parse(Gmail.Users.Labels.list("me")).labels;
let hdr = ["Name","Vis","Type","id"]
let o = labels.map(obj => [obj.name,obj.messageListVisibility,obj.type,obj.id]);
const ss = SpreadsheetApp.getActive();
const sh = ss.getSheetByName('Sheet0');
sh.clearContents();
o.unshift(hdr);
sh.getRange(1,1,o.length,o[0].length).setValues(o).sort({column:1,ascending:true});
}
Gmail API needs to be enabled
In regard to your last comment I added this code to create sub labels to an existing label
function createLabelsAndSubLabel() {
const labels = ["Q1/3/1","Q1/3/2","Q1/3/3"]
labels.forEach(l => GmailApp.createLabel(l))
}