Finally I found:
appModule
.factory('testFactory', ['Restangular', function(Restangular) {
return {
getFriendList: Restangular
.all('api/users/getfriendsinvitations/')
.getList();
}
}]);
testFactory.getFriendList.then(function(homeFriends) {
$scope.homeFriends = homeFriends;
}