Waiting for $rootScope value to resolve in Angular before page load

Question

So I'm running into this problem where I'm using ngView and I have a navigation bar that is static throughout like so:

<div ng-include="'views/nav.html'" ng-controller="NavCtrl"></div>
<div class="container-fluid" ng-view=""></div>

This nav.html, the navigation bar, displays a certain set of functions (Login, Register) if the user is logged out (using ng-show) and other menu options if the user is logged in. Because of the heavy use of current user, I've put this information in the $rootScope like this: $rootScope.currentUser - returns user object, and $rootScope.signedIn - return boolean.

Basically, I want to delay the navbar from loading until $rootScope.signedIn is loaded and either true or false, and $rootScope.currentUser is an object or undefined.

I've tried messing around with creating promises in my app.config routes, but I'm not sure how I can return a promise to the permanent view state.

Any help is appreciated.

Edit :

Here is the service in which I broadcast my login. This fires anytime a user is authenticated/logged in or anytime they logout:

    var authClient = new FirebaseSimpleLogin(refDownload, function(error, user) {
        if (error) {
            incorrectLogin(error.code);
        }
        if (user) {
            // user authenticated
            $rootScope.$broadcast('login');
            correctLogin(user.id);
        } else {
            // user is logged out
            $rootScope.$broadcast('logout');
        }
    });

This service is injected into the NavCtrl controller in the following way:

    $scope.isHidden = true;

    $scope.$on('login', function() {
        console.log('login broadcast');
        $scope.isHidden = false;
    });

    $scope.$on('logout', function() {
        console.log('broadcast logout');
        $scope.isHidden = true;
    });

The template for this controller is nav.html that looks like this:

<div class="col-xs-4 centered" id="nav-hover"  ng-show="isHidden">
    <ul class="nav navbar-nav">
        <li id="nav-login"><a ng-href="#/login"><span class="glyphicon glyphicon-log-in">&nbsp;Login</span></a></li>
    </ul>
</div>

<div class="col-xs-4 centered" id="nav-hover" ng-show="isHidden">
    <ul class="nav navbar-nav">
        <li id="nav-login"><a ng-href="#/register"><span class="glyphicon glyphicon-edit">&nbsp;Register</span></a></li>
    </ul>
</div>


<div class="col-xs-2 centered" id="nav-hover">
    <ul class="nav navbar-nav" ng-hide="isHidden">
        <li ng-class="{{ chatCat.active }}"><a ng-href="{{ chatCat.url }}"><span class="{{ chatCat.icon }}"></span></a></li>
    </ul>
</div>

Again, this view is bound to NavCtrl. When logging users in, I use AuthCtrl as follows:

    $scope.login = function() {
        if ($scope.user !== undefined) {
            Auth.login($scope.user);
            $location.path('/dexter');
        } else {
            console.log('nothing entered');
        }               
    };

When I try to login, the nav view does not update with the new values, although the broadcast is fired from the service with 'logged in'.

Auth service:

'use strict';

app.factory('Auth',
    function($rootScope, $location, $firebase, $firebaseSimpleLogin, firebaseUrl) {

    var refDownload = new Firebase(firebaseUrl + 'housemates');

    var sync = $firebase(refDownload); 

    var ref = sync.$asObject();

    var authClient = new FirebaseSimpleLogin(refDownload, function(error, user) {
        if (error) {
            incorrectLogin(error.code);
        }
        if (user) {
            // 1
            // user authenticated
            correctLogin(user.id);
        } else {
            // user is logged out
            // $rootScope.signedIn = false;
        }
    });

    var Auth = {

        housemates: ref,

        changeColor: function(color) {
            var id = $rootScope.currentUser.id.toString();
            refDownload.child(id).update({ color: color });
            $rootScope.currentUser.color = color;
        },


        create: function(authUser, usr) {
            refDownload.child(authUser.id).set({
                initials: usr.initials,
                email: authUser.email,
                password: usr.password,
                color: 'Blue',
                id: authUser.id,
                uid: authUser.uid,
                rememberMe: true,
            });

        },

        // 3
        findById: function(id) {
            refDownload.on('value', function(snapshot) {
                var userObject = snapshot.val();
                // 4 - sets currentUser
                //$rootScope.currentUser = userObject[id];
                var currentUser = userObject[id];
                Auth.setUser(currentUser);
                // $rootScope.signedIn = true;
            }, function (error) {
                console.log(error);
            });
        },

        login: function(user) {
            authClient.login('password', {
                email: user.email,
                password: user.password,
                rememberMe: true
            });
        },

        logout: function() {
            delete $rootScope.currentUser;
            delete $rootScope.signedIn;
            delete $rootScope.error;
            return authClient.logout();
        },

        register: function(user) {
            var userSimple = user;
            authClient.createUser(user.email, user.password, function(error, user) {
                if(!error) {
                    var userComplex = user;
                    Auth.login(userSimple);
                    Auth.create(userComplex, userSimple);
                    return user;
                } else {
                    console.log(error);
                }
            });

        },

        setUser: function(aUser) {
            console.log('setuser ran');
            $rootScope.currentUser = aUser;
            console.log('setUser: ' + $rootScope.currentUser);
        },

        isLoggedIn: function() {
            console.log($rootScope.currentUser);
            return ($rootScope.currentUser) ? $rootScope.currentUser : false;
        },


    };

    // 2
    function correctLogin(id) {
        Auth.findById(id);
    }

    function incorrectLogin(error) {
        alert(error);
        $rootScope.error = error;
    }

    return Auth;


});

Answer 1

With a bit of $rootScope.$broadcast and ng-hide on the menu, this could be easily accomplished. See this plunker

The html:

<!DOCTYPE html>
<html ng-app="plunker">

  <head>
    <meta charset="utf-8" />
    <title>AngularJS Plunker</title>
    <script>document.write('<base href="' + document.location + '" />');</script>
    <link rel="stylesheet" href="style.css" />
    <script data-require="angular.js@1.2.x" src="https://code.angularjs.org/1.2.25/angular.js" data-semver="1.2.25"></script>
    <script src="app.js"></script>
  </head>

  <body ng-controller="MainCtrl">
  <div ng-include="'nav.html'" ng-controller="NavCtrl" ng-hide="isHidden"></div>
  <button class="btn" ng-click="login()">Login</button>
  <button class="btn" ng-click="logout()">Logout</button>
  </body>

</html>

The javascript:

var app = angular.module('plunker', []);

app.controller('MainCtrl', function($scope, $rootScope) {
  $scope.login = function() {
    $rootScope.$broadcast("login");
  }

  $scope.logout = function() {
    $rootScope.$broadcast("logout");
  }
});

app.controller('NavCtrl', function($scope) {
  $scope.isHidden = true;
  $scope.$on('login', function() {
    console.log("logged in");
    $scope.isHidden = false;
  });

  $scope.$on('logout', function() {
    console.log("logged out");
    $scope.isHidden = true;
  });
});

Answer 2

OK, if the way i suggested isn't working for you, here is a second possible solution ( plunker )

The base idea is to have a service (in this case a factory) in which you set the logged in user name and then in the nav controller use $watch to watch changes to the authentication status in the service. And the code:

<!DOCTYPE html>
<html ng-app="plunker">

  <head>
    <meta charset="utf-8" />
    <title>AngularJS Plunker</title>
    <script>document.write('<base href="' + document.location + '" />');</script>
    <link rel="stylesheet" href="style.css" />
    <script data-require="angular.js@1.2.x" src="https://code.angularjs.org/1.2.25/angular.js" data-semver="1.2.25"></script>
    <script src="app.js"></script>
    <script src="Auth.js"></script>
  </head>

  <body ng-controller="MainCtrl">
  <div ng-include="'nav.html'" ng-controller="NavCtrl" ng-hide="isHidden"></div>
  <button class="btn" ng-click="login()">Login</button>
  <button class="btn" ng-click="logout()">Logout</button>
  </body>

</html>

The javascript:

var app = angular.module('plunker', []);

app.controller('MainCtrl', function($scope, $rootScope, Auth) {
  $scope.login = function() {
    var user = "iris"
    Auth.setUser(user);
  }

  $scope.logout = function() {
    Auth.setUser(null);
  }
});

app.controller('NavCtrl', function($scope, Auth) {
  $scope.isHidden = true;

  $scope.$watch(Auth.isLoggedIn, function (value, oldValue) {

    console.log("authentication changed");

    if(!value && oldValue) {
      console.log("logged out");
      $scope.isHidden = true;
    }

    if(value) {
      console.log("logged in");
      $scope.isHidden = false;
    }

  }, true);


});

and the service:

app.factory('Auth', function() {
  var user;

  return {
    setUser: function(aUser) {
      user = aUser;
    },
    isLoggedIn: function() {
      console.log(user);
      return (user) ? user : false;
    }
  }
})

Answer 3

@zszep $broadcast answer solved the problem with one caveat. It was necessary to add $scope.$apply() following each of the $scope.isHidden commands in NavCtrl. This forced a page refresh of sorts and the Nav view updated.