Angularjs async requests - angularjs

Question

Controller 1
var promise = UserService.userexists(groupid);
promise.then(
},
function (response) {
}
);
Controller 2
var promise = UserService.userexists(groupid);
promise.then(
},
function (response) {
}
);
Service
app.factory("UserService", function ($q, $timeout) {
return {
userexists: function (groupid) {
var deferred = $q.defer();
//this is just to keep a pointer to parent scope from within promise scope.
IsCurrentUserMemberOfGroup(groupid, function (isCurrentUser) {
if (isCurrentUser) {
deferred.resolve(isCurrentUser);
}
else {
deferred.reject(isCurrentUser);
}
});
return deferred.promise;
}
}
});
function IsCurrentUserMemberOfGroup(groupId, OnComplete) {
var currentContext = new SP.ClientContext.get_current();
var currentWeb = currentContext.get_web();
var currentUser = currentContext.get_web().get_currentUser();
currentContext.load(currentUser);
var allGroups = currentWeb.get_siteGroups();
currentContext.load(allGroups);
var group = allGroups.getById(groupId);
currentContext.load(group);
var groupUsers = group.get_users();
currentContext.load(groupUsers);
currentContext.executeQueryAsync(OnSuccess, OnFailure);
function OnSuccess(sender, args) {
var userInGroup = false;
var groupUserEnumerator = groupUsers.getEnumerator();
while (groupUserEnumerator.moveNext()) {
var groupUser = groupUserEnumerator.get_current();
if (groupUser.get_id() == currentUser.get_id()) {
userInGroup = true;
break;
}
}
OnComplete(userInGroup);
}
function OnFailure(sender, args) {
OnComplete(false);
}
}
I have controller 1 and controller 2 on the same page, both use the same service to check the user exist in a specific group. Problem is the service runs the check user method (IsCurrentUserMemberOfGroup) for each controller. Is there a way so that I execute the method once and other controllers can use it?
This is a sharepoint 2010 environment.
Thanks

Answer 1

You could cache the result in your service, maybe something like
app.factory("UserService", function ($q, $timeout) {
return {
var cache = {};
userexists: function (groupid) {
var deferred = $q.defer();
if (cache[groupif]) {
deferred.resolve(cache[groupif]);
return deferred.promise;
}
IsCurrentUserMemberOfGroup(groupid, function (isCurrentUser) {
if (isCurrentUser) {
cache[groupif] = isCurrentUser;
deferred.resolve(isCurrentUser);
}
else {
deferred.reject(isCurrentUser);
}
});
return deferred.promise;
}
}
});