Troubleshooting problem with Angular $scope and ng-if/ng-show: View status remains unchanged

Utilizing Firebase for authentication in my web app, I have implemented buttons on various pages that should only be visible when the admin is logged in. Despite using ng-if to display the button if 'loggedin' equals true, the buttons refuse to appear even though console logging confirms 'loggedin' is changing correctly.

I'm at a loss as to what could be causing this issue. While consulting the Angular docs and exploring $scope, ngIf, and ngShow directives, I haven't been able to find a solution. I even referred to this StackOverflow post, where others seemed to have success with the same process. Unfortunately, it's not working for me.

Below is a snippet of the controller code:

app.controller('welcomeCtrl', function ($scope, welcomeData, $routeParams, $location) {

var ref = new Firebase('https://mywebapp.firebaseio.com/');

  //authentication check
  var auth = new FirebaseSimpleLogin(ref, function (error, user) {
    if (error) {
      // an error occurred while attempting login
      console.log(error);
    }
    // no user logged in
     else if (user === null) {
      console.log("Not logged in");
    }
    // normal user logged in
    else if (user.id !== "47f0b82c-59d2-4bcd-8arc-ecb438eb0163") {
      console.log("You are logged in as normal user");
    }
    // admin logged in
    else {
      console.log("Logged in as admin");
      $scope.loggedin = true;
      console.log("logging the scope.loggedin as admin " + $scope.loggedin);
    }
  });

  $scope.loggedin = false;
  console.log("logging scope.loggedin " + $scope.loggedin);

  var authCheck = function () {
    console.log("logging the scope in authCheck " + $scope.loggedin);
    return auth.user !== null;
  };
  authCheck();

The following HTML element does not update accordingly:

<div ng-show="loggedin">
  <a class="btn waves-effect waves-red" ng-href="/#/editWelcome/{{welcome._id}}">Update
  </a>
</div>

If anyone has any suggestions or insights into what I might be missing or doing wrong, I would greatly appreciate any help. Thank you!

Answer №1

Initially, FirebaseSimpleLogin has been marked as deprecated. The authentication methods have now been integrated into the main Firebase library. You can incorporate the onAuth callback for your setup.

The reason why the $scope.loggedin value is not updating is due to Firebase's callbacks executing outside of Angular's digest scope. To notify Angular about this update, you can either utilize $scope.$evalAsync() or Firebase's AngularFire library.

If you opt for $evalAsync, enclose your $scope modifications within a function in your else block:

// admin logged in
else {
  console.log("Logged in as admin");
  $scope.$evalAsync(function() {
     $scope.loggedin = true;
  });
}

Answer №2

Special thanks to Sherali Turdiyev for providing the solution to this particular challenge.

 //authentication verification
 var auth = new FirebaseSimpleLogin(ref, function (error, user) {
if (error) {
  // error occurred during login attempt
  console.log(error);
}
// no user currently logged in
 else if (user === null) {
  console.log("Not logged in");
}
// regular user logged in
else if (user.id !== "47f0b82c-59d2-4bcd-8arc-ecb438eb0163") {
  console.log("Logged in as a regular user");
}
// admin is logged in
else {
  console.log("Logged in as admin");
  $scope.loggedin = true;
  console.log("The scope.loggedin has been set to admin: " + $scope.loggedin);
}
// issue resolved with this step
$scope.$apply();
 });

Upon consulting the documentation for $scope.$apply(), I realized that the problem lied within the digest cycle. The utilization of $scope.$apply() triggers the digest process, resulting in an update to the scope. Furthermore, I acknowledged that executing this code within the controller was not ideal. It's time to transform this into a directive. Once again, thank you for the assistance!

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