ParseConflictHelperFn.js

Parse.Cloud.beforeSave("TestObject", function(request, response) {

    ensureNotStale(request.object, response.error, function() {

        // Update is not stale. Add any other code here
        console.log('doing some work here with the fresh object');

        response.success();
    });
});

function ensureNotStale(incommingObj, reject, resolve) {

    var versionAttrName = "version";
    var className = incommingObj.className;
    var id = incommingObj.id;

    if (incommingObj.isNew()) {
        console.log(className + ' "' + id + '" is new so setting ' + versionAttrName + ' to 1');
        incommingObj.set(versionAttrName, 1);
        resolve();
        return;
    }

    var incommingVersion = incommingObj.get(versionAttrName);
    incommingObj.increment(versionAttrName);

    var query = new Parse.Query(className);
    query.get(id, {
        success: function(latest) {

            var latestVersion = latest.get(versionAttrName);
            var upToDate = incommingVersion === latestVersion;

            if (!upToDate) {
                var msg = 'StaleUpdate: Could not update stale ' + className + ' "' + id + '". ' +
                          'Incomming version was ' + incommingVersion + ', latest is ' + latestVersion;
                console.log(msg);
                reject(msg);
            } else {
                // console.log(className + ' "' + id + '" is up to date at version ' + latestVersion + '. Letting op proceed');
                resolve();
            }
        },
        error: function(object, error) {
            if (error.code === Parse.Error.OBJECT_NOT_FOUND) {
                // hmm, doesn't exist. Oh well, carry on
                console.warn('Could not find previous ' + className + ' with ID "' + id + '"');
                resolve();
            } else {
                console.error('Could not load previous ' + className + ' with ID "' + id + '". Error was: ' + error);
                reject('Error checking for previous version of ' + className);
            }
        }
    });
}