angular $resource receive extra information - angularjs

Question

I am using ng-resource to do ajax request. I want to send extra info besides the data.
For example, I have an article entity on my server
exports.fetchArticle = function(req, res, next) {
var article = req.article
return res.json({data: article, message: 'success fetch article'})
}
The reason I wrap it is that, in the case of deletion, it makes no sense to send data, I can just return res.json({data: null, message: 'deleted successfully'})
on my client side, I have:
$scope.fetchArticle = function() {
Article.get({articleId: $routeParams.articleId}, function(response) {
$scope.article = response.data
$scope.ajaxSuccess = response.message
}, function(err) {
$scope.ajaxError = err.data.message
})
}
$scope.article is not an instance of ng-resource anymore, thus I can't do further request with $scope.article, i.e. this will cause error, since $scope.article is a plain json object:
$scope.article.$update(function(response) {...})
If I simply return res.json(article) from server, it works, but I can't send along the message.
The reason I dont generate the message from client but fetch from server is that, the error message is from server, I want to keep success message consistent with the error message.
Is there any other elegant way to send the message?

Answer 1

Assuming that all your servers responses follow this format:
{
data: {/*...*/},
message: 'some message'
}
You could use $http's transformResponse for that, so that you get an ngResource instance that is your returned object while still processing your message. For that, you need a transform-function:
function processMessage(data, message) {
//Do whatever you want with your message here, like displaying it
}
function transform(response) {
processMessage(response.data,response.message);
var data = response.data;
delete response.data;
delete response.message;
for(var attributeName in data) {
response[attributeName] = data[attributeName];
}
return response;
}
Then you can add this function to $http's default transfroms in the config of your app:
angular.module("yourApp",[/* ... */])
.config(function($httpProvider){
//....all your other config
$httpProvider.defaults.transformResponse.unshift(transform);
});
Now all repsonses from $http get transformed by this function, triggering processMessage and leaving you with a ngResource instance of the returned object.