Change Gmail label once attachment is uploaded to drive - google-apps-script

Question

How can you remove the existing label "Global Alcohol" & add a "Global Processed" label to the email messages which have had the attachments uploaded to Google Drive using the following code? I must give credit to Cooper who answered my first question & helped me get the uploads working.
function saveAttachmentInFolder(){
var folder = DriveApp.getFolderById('xxxxxxxxxxxxx');
var userId = "myemail#gmail.com";
var query = "label:Global Alcohol";
var res = Gmail.Users.Messages.list(userId, {q: query});//I assumed that this works
res.messages.forEach(function(m){
var attA=GmailApp.getMessageById(m.id).getAttachments();
attA.forEach(function(a){
var ts=Utilities.formatDate(new Date(),Session.getScriptTimeZone(), "yyMMddHHmmss");
folder.createFile(a.copyBlob()).setName(a.getName()+ts);
});
});
}
I have read the API documentation & can see that you need to use the following code to modify the Labels. However I am stuck with how to integrate it into the function above.
function modifyMessage(userId, messageId, labelsToAdd, labelsToRemove, callback) {
var request = gapi.client.gmail.users.messages.modify({
'userId': userId,
'id': messageId,
'addLabelIds': labelsToAdd,
'removeLabelIds': labelsToRemove
});
request.execute(callback);
}

Answer 1

You were on the right track with the modification call, but the formatting is slightly off. The trick here is that you need to use the label IDs, so I wrote a new function getLabelsByName() that allows you to perform that lookup.
function saveAttachmentInFolder(){
var folder = DriveApp.getFolderById('xxxxxxxxxxxxx');
var userId = "myemail#gmail.com";
var query = "label:Global Alcohol";
var labels = getLabelsByName(userId, ["Global Alcohol", "Global Processed"]);
var res = Gmail.Users.Messages.list(userId, {q: query});//I assumed that this works
res.messages.forEach(function(m){
var attA=GmailApp.getMessageById(m.id).getAttachments();
attA.forEach(function(a){
var ts=Utilities.formatDate(new Date(),Session.getScriptTimeZone(), "yyMMddHHmmss");
folder.createFile(a.copyBlob()).setName(a.getName()+ts);
});
// Remove the old label & add the new one
Gmail.Users.Messages.modify({
addLabelIds: [labels["Global Processed"].id],
removeLabelIds: [labels["Global Alcohol"].id]
}, userId, m.id);
});
}
/**
* Lookup any number of labels by their name using the advanced Gmail service.
* #param {String} userId - The user's email address or "me" to get your own
* #param {String[]} labelNames - An array of labels names to search for
* #returns {Label{}} - Map of labels identified by label name
* https://developers.google.com/gmail/api/v1/reference/users/labels
*/
function getLabelsByName(userId, labelNames) {
var response = Gmail.Users.Labels.list(userId);
var selectedLabels = {};
for (var i = 0; i < response.labels.length; i++) {
var label = response.labels[i];
if (labelNames.indexOf(label.name) != -1) {
selectedLabels[label.name] = label;
}
}
return selectedLabels;
}