Inherit from calStorageCalendar

Hi,

I am developing an AddOn, that creates calendars using:

let newCalendar = calManager.createCalendar("storage", cal.makeURL('moz-storage-calendar://'));

These calendars depend on external sources, at the moment they are only updated during load. I also would like to trigger an update, if the user clicks on the big lightning synchronize button.

If I understood correctly, I have to create a custom provider which returns true for canRefresh and implements refresh().


I have three questions:

1. How do I generate a unique ID for my provider, can I just pick one?

2. How do I inherit my custom provider from calStorageCalendar? I do not want to implement all the methods by myself, I want to use everything from the default StorageCalender. So if something changes in future versions of Thunderbird, I do not have to catch up.

3. Do I have to choose a different URL schema, or can I use "moz-storage-calendar://" as well? 


This is what I use at the moment in my Manifest:

component {B99A6D64-2C89-11DC-9698-529656D89593} components/calMyCustomProvider.js
contract @mozilla.org/calendar/calendar;1?type=mycustomprovider {B99A6D64-2C89-11DC-9698-529656D89593}

And this is calMyCustomProvider.js:

Components.utils.import("resource://gre/modules/XPCOMUtils.jsm");
Components.utils.import("resource://calendar/modules/calUtils.jsm");
 
function calMyCustomProvider() {
    this.initProviderBase();
}

calMyCustomProvider.prototype = {
    __proto__: cal.ProviderBase.prototype,
    
    classDescription: "My Custom Calendar Provider",
    contractID: "@mozilla.org/calendar/calendar;1?type=mycustomprovider",
    classID:  Components.ID("{B99A6D64-2C89-11DC-9698-529656D89593}"),

    QueryInterface: function cTBS_QueryInterface(aIID) {
        if (!aIID.equals(Components.interfaces.nsISupports) &&
            !aIID.equals(Components.interfaces.calICalendar)) {
            throw Components.results.NS_ERROR_NO_INTERFACE;
        }
        return this;
    },
    
    get type() {
        return "mycustomprovider";
    },
        
    get canRefresh() {
        return true;
    },
    
    refresh: function cTBS_refresh() {
        // DO SOMETHING HERE 
        // tell observers to reload everything
        this.mObservers.notify("onLoad", [this]);
    }
};

However, creating a calendar with:

let newCalendar = calManager.createCalendar("mycustomprovider", cal.makeURL('moz-storage-calendar://'));

gives a fatal error on calendar creation. Any hint on what I am doing wrong would be great.

Thanks,
John