>Hi everybody,
>
>I have two pages in the same form that need to access the same data.
>
>Each of the pages is controlled by its own controller and both have this code in the init:
>
>

>invoicesService.getMetaData().then(function (data) {
>                        $scope.invoicesMetaData = data;
>
>                    });

>
>So, I want to somehow adjust the service code to not invoke the method twice. Here is what I attempted to do but it's not working:
>
>

>app.factory('invoicesService', ['$http', '$q', function($http, $q) {
>
>        var metaData = null;
>
>        var getMetaData = function () {
>            if (angular.isObject(metaData))
>                return metaData;
>
>            var deferred = $q.defer();
>            $http.get('/api/invoices/metadata')
>                .success(function (data) {
>                    metaData = data;
>                    deferred.resolve(data);
>                    
>                })
>                .error(function (data, status, header, config) {
>                    deferred.reject(status);
>                });
>            return deferred.promise;
>        };

>
>I still get 2 hits in my API controller. Do you see how should I change the above to avoid the second call after the first one was already made?

The problem is that the second call could arrive before the $http asynchronous call completes. Something like this might work (untried):

app.factory('invoicesService', ['$http', '$q', function ($http, $q) {

        var metaData = null;
        var inProcess = false;
        var getMetaData = function () {

            while (inProcess === true) {
            }

            if (angular.isObject(metaData))
                return metaData;
            inProcess = true;
            var deferred = $q.defer();
            $http.get('/api/invoices/metadata')
                .success(function (data) {
                    metaData = data;
                    inProcess = false;
                    deferred.resolve(data);

                })
                .error(function (data, status, header, config) {
                    deferred.reject(status);
                });
            return deferred.promise;
        }
    }]);

Angular doesn't have a synchronous option for $http so an altenative would be to fall back to using a XMLHttpRequest synchronously:

var req = new XMLHttpRequest();
    req.open('GET', '/api/invoices/metadata', false); 
    req.send(null);

    if (req.status === 200) {
        //etc........