AngularJS - Bypass the $http promises object managment - angularjs

Question

I've a service like this:
angular.module('module')
.factory('UserList', function ($http) {
return {
getUserList: $http.get('/portal-services/NemesysPortalBackend/rest/user/all')
};
});
this constraint me to do
UserList.getUserList.then(function(res){$scope.data = res.data;})
in every controller where I need it.
Is there any way to "facade" it to simply have
$scope.data = UserList.getUserList();
Thanks

Answer 1

I'm making an assumption here that the user list doesn't change often, so this way you can cache it to a variable... otherwise you will need to make a call each time you expect the list changes (or reload the list using an interval?)
Fetching data before it's really needed is called "Eager loading"
angular.module('module').factory('UserList', function ($http, $q, $interval) { // import $q as well
var userList = []; // initialized as blank array
var refreshList = function(){
var deferred = $q.defer();
$http.get('/portal-services/NemesysPortalBackend/rest/user/all').then(
function(successResponse){
userList = successResponse.data;
deferred.resolve(successResponse);
},function(failureResponse){
// do something on error?
deferred.reject(failureResponse);
});
return deferred.promise;
}
refreshList(); // eager load, run right away
// i don't recommend this next line, there are better ways of doing this
$interval(refreshList(), 1000*60); // get new list every 60 seconds
return {
getUserList: function(){ return userList; }, // return user list only
refreshList: function(){ refreshList(); } // return promise which getting new list
};
});
Again, I don't recommend using $interval to reload the list, but instead call refreshList any time updates are made to the user list
Ex:
angular.module('module').controller('userCtrl', function(UserList) {
$scope.data = UserList.getUserList();
// once you change the user list, call a refresh
UserList.addUser().then(UserList.refreshList()).then(function(){
$scope.data = UserList.getUserList();
);
});

Answer 2

You cannot do this because JavaScript is single-threaded. This means, that when you use some call that is asynchronous, you cannot ever make it synchronous. There is no waiting(*) in Javascript. You cannot block your function call to wait for the results from the server.
Even if you tried as hard as this:
function getResult() {
var result;
UserList.getUserList.then(function(res) {
result = res.data; // this should break the loop below
});
while (!result) {}; // active waiting, wasting CPU cycles
return result;
}
...it wouldn't work because the callback function will not be executed until the currently running code (i.e., the infinite loop) finishes. An infinite loop like this would freeze the whole application forever.
(*) this doesn't mean that you cannot schedule functions to be called at some point later. Promises and closures help a lot with it.