AngularJs $resource save throwing ERR_CONTENT_LENGTH_MISMATCH - node.js

Question

Using AngularJs $resource for updating the existing data. calling save on resource.
This is my service.
app.factory('SubscriptionsService', function ($resource, $q) {
// $resource(url, [paramDefaults], [actions], options);
var resource = $resource('/api/subscriptions');
var factory = {};
factory.updateSubscriptions = function (updatedSubscriptions) {
console.log("SubscriptionsService: In updateSubscriptions. "+JSON.stringify( updatedSubscriptions));
var deferred = $q.defer();
resource.save(updatedSubscriptions,
function(response){
deferred.resolve(response);
},
function(response){
deferred.reject(response);
}
);
return deferred.promise;
}
return factory;
});
And API looks like the following.
exports.update = function (req, res) {
console.log("In Subscriptions API: Update invoked.");
if (req.body == null || req.body.items == null || req.body.items == 'undefined') {
return res.json({"status":0,"message":"no items present."});
}
var items = req.body.items;
console.log("About to call update on db."+items);
db.update(items,function(error,result,failedItems){
if(error)
return res.json({"status":-1,"message":error.message,"failedItem":failedItems});
return res.json({"status":1,"message":result,"failedItem":failedItems});
})
}
And controller as follows
$scope.confirmUpdates = function () {
if ($scope.updatedItems.length > 0) {
var updatedSubscriptionLevels = { "items": $scope.updatedItems };
var promise = SubscriptionsService.updateSubscriptions(updatedSubscriptionLevels);
promise.then(
function(response){
console.log("Response received from API.");
var statusCode = response.status;
console.log("statusCode: "+statusCode);
},
function(message){
console.log("Error message: "+message);
}
);
}
}
Strange part is data is getting updated. But promise receiving an error.
POST xxxxxx/testapi/subscriptions net::ERR_CONTENT_LENGTH_MISMATCH
I doubt I am not implementing/consuming resource in a right way. Can anybody advise?
Thanks.

Answer 1

I think I found the mistake.
There were couple of things I was not handling in a right way.
I didn't post my db code in mt question where the root cause was present.
if(itemsToUpdate!=null && itemsToUpdate.length>0){
var failedItems = []; // Holds failed items while updating.
console.log("Items to update: "+itemsToUpdate);
for(var index=0;index<itemsToUpdate.length;index++){
var item = itemsToUpdate[index];
console.log(item);
subscriptionLevels.update(
{_id:item._id},
{$set:{title:item.title,daysValid:item.daysValid,subscriptionFee:item.subscriptionFee}},
function(error,rowsEffected){
if(error){
console.log(error);
// Error occurred. Push it to failed items array.
failedItems.push({"title":item.title,"message":error.message});
}
else{
console.log("Number of rows updated: "+rowsEffected);
}
}
);
}
callback(null,"SUCCESS",failedItems);
}
else {
callback(null, "NO_ITEMS", []);
}
I missed if - else condition and invoking callback multiple times which was causing the issue.