Writing Add-on manifest files - google-apps-script

Question

I created a GAS script file on my Drive using the example from Packt's book 'Learning Google Apps Script. My question is how do I make this into an Add-On. Not quite sure on the manifest file I need to create (even after reading https://developers.google.com/gmail/add-ons/how-tos/building).
function saveEmailAttachmentsToDrive(){
// Create 'Gmail Attachments' folder if not exists.
createFolder_('Gmail attachments');
// Get inbox threads starting from the latest one to 100.
var threads = GmailApp.getInboxThreads(0, 100);
var messages = GmailApp.getMessagesForThreads(threads);
var folderID = PropertiesService.getUserProperties()
.getProperty("FOLDER");
var file, folder = DriveApp.getFolderById(folderID);
for (var i = 0 ; i < messages.length; i++) {
for (var j = 0; j < messages[i].length; j++) {
if(!messages[i][j].isUnread()){
var msgId = messages[i][j].getId();
// Assign '' if MSG_ID is undefined.
var oldMsgId = PropertiesService.getUserProperties()
.getProperty('MSG_ID') || '';
if(msgId > oldMsgId){
var attachments = messages[i][j].getAttachments();
for (var k = 0; k < attachments.length; k++) {
PropertiesService.getUserProperties()
.setProperty('MSG_ID', messages[i][j].getId());
try {
file = folder.createFile(attachments[k]);
Utilities.sleep(1000);// Wait before next iteration.
} catch (e) {
Logger.log(e);
}
}
}
else return;
}
}
}
};
function createFolder_(name) {
var folder, folderID, found = false;
/*
* Returns collection of all user folders as an iterator.
* That means it do not return all folder names at once,
* but you should get them one by one.
*
*/
var folders = DriveApp.getFolders();
while (folders.hasNext()) {
folder = folders.next();
if (folder.getName() == name) {
folderID = folder.getId();
found = true;
break;
}
};
if (!found) {
folder = DriveApp.createFolder(name);
folderID = folder.getId();
};
PropertiesService.getUserProperties()
.setProperty("FOLDER", folderID);
return folderID;
}
My question is how do I make this into an Add-On. Not quite sure on the manifest file I need to create (even after reading https://developers.google.com/gmail/add-ons/how-tos/building).

Answer 1

The JSON for the manifest file for the gmail part is:
"gmail": {
"name": "My Gmail Add-on",
"logoUrl": "https://www.example.com/hosted/images/2x/my-icon.png",
"primaryColor": "#4285F4",
"secondaryColor": "#00BCD4",
"authorizationCheckFunction": "get3PAuthorizationUrls",
"contextualTriggers": [{
"unconditional": {},
"onTriggerFunction": "buildAddOn"
}]
That must be in addition to what is already there. A manifest file at it's very basic, looks like this:
{
"timeZone": "America/New_York",
"dependencies": {
},
"exceptionLogging": "STACKDRIVER"
}
You are going to make it look like the following:
{
"timeZone": "America/New_York",
"dependencies": {
},
"gmail": {
"name": "My Gmail Add-on",
"logoUrl": "https://www.example.com/hosted/images/2x/my-icon.png",
"primaryColor": "#4285F4",
"secondaryColor": "#00BCD4",
"authorizationCheckFunction": "get3PAuthorizationUrls",
"contextualTriggers": [{
"unconditional": {},
"onTriggerFunction": "buildAddOn"
}]
},
"exceptionLogging": "STACKDRIVER"
}
Use your timeZone, and your settings. Note that there are no dependencies listed, but leave that part in.

Answer 2

manifest.json is generated automatically by the Apps Script engine. It is hidden by default, but you can view it by toggling View > manifest file to see the structure.
When you're ready to test the AddOn, you can go to Publish > Deploy as web add on. If you're uploading from the cloud editor, you do not need to add a separate manifest file in the web store listing.
The development documentation covers deployment methods in detail.