When there is an infinite loop in the run block, the $http success callback in the factory is not triggered

Question

When there is an infinite loop in the run block, the $http success callback in the factory is not triggered

Take a look at my code with the relevant parts highlighted:

authorization.js

while loop is omitted, I encounter this error:

Cannot read property 'toString' of undefined

This error stems from attempting to call toString on currentUser._id while it's still undefined. My belief is that initially, Auth.getCurrentUser() returns a reference to {}. Upon assignment, {} should be assigned to currentUser, allowing the code to continue. However, since the response hasn't arrived yet, currentUser cannot be updated. Therefore, I resorted to using the while loop to halt execution until the response arrives. Surprisingly, the loop runs endlessly! Shouldn't the response eventually arrive, update currentUser, and turn !currentUser._id into false, breaking the loop?

Initially, factory cb and then userId get logged. Yet, the infinite loop kicks in without ever reaching

success</code/>. Doesn't asynchronous behavior dictate otherwise? How does the loop manage to interfere with the request completion? What exactly is happening here?</p>

<p>The call itself isn't causing issues; sans the <code>while

loop, the success callback gets triggered and logs success. Furthermore, upon console.dir(currentUser) in authorization.js, the user's info is displayed. Strangely though, using console.log(currentUser) yields an empty object. The reason behind this remains unclear.

javascript angularjs

Answer 1

Answer №1

From what I understand, due to Javascript being single-threaded, the http callback may not have access to CPU time to handle the response while the thread is stuck in the while loop.

Answer 2

From what I understand, due to Javascript being single-threaded, the http callback may not have access to CPU time to handle the response while the thread is stuck in the while loop.

Answer 3

Answer №2

It seems like the issue here is that your authentication processes are being checked asynchronously, which is likely due to the HTTP call required for validation.

At the moment when the script runs, the currentUser object from Auth.getCurrentUser() is not yet filled with the necessary data because it is being assigned at a later point in an asynchronous block:

angular.copy(data, currentUser);

As a result, it's possible that the property _id has not been added to currentUser yet, leading to the function toString() being called on undefined.

To address this issue, you may want to consider using callbacks or promises. If you have control over the auth.factory.js file, instead of returning the object synchronously in getCurrentUser, you could return a promise or callback that resolves once the HTTP request is complete.

Additionally, it's worth noting that the console.dir in your script may not display any data as it runs before the object is fully populated.

Answer 4

It seems like the issue here is that your authentication processes are being checked asynchronously, which is likely due to the HTTP call required for validation.

At the moment when the script runs, the currentUser object from Auth.getCurrentUser() is not yet filled with the necessary data because it is being assigned at a later point in an asynchronous block:

angular.copy(data, currentUser);

As a result, it's possible that the property _id has not been added to currentUser yet, leading to the function toString() being called on undefined.

To address this issue, you may want to consider using callbacks or promises. If you have control over the auth.factory.js file, instead of returning the object synchronously in getCurrentUser, you could return a promise or callback that resolves once the HTTP request is complete.

Additionally, it's worth noting that the console.dir in your script may not display any data as it runs before the object is fully populated.

Answer 5

Answer №3

In Angular, services act as singletons which means they are created only once when needed and then the same instance is passed around as a dependency. This ensures that the code to fetch the current user is executed just once. However, if the user is not logged in, nothing will happen.

To handle this scenario using cookies, you can check if the user data is stored in the cookie before proceeding with your code to get the current user. If the current user is null, it indicates that the user is not logged in and you need to query the API for the data. In such cases, you should execute the code inside a promise.

Since the logic for handling both scenarios (user logged in / not logged in) is the same, it is recommended to move this code into a service for reusability.

Additionally, it is advisable to broadcast events each time the user logs in or out. This allows different parts of the application to listen to these events and react accordingly based on the information received.

Answer 6

In Angular, services act as singletons which means they are created only once when needed and then the same instance is passed around as a dependency. This ensures that the code to fetch the current user is executed just once. However, if the user is not logged in, nothing will happen.

To handle this scenario using cookies, you can check if the user data is stored in the cookie before proceeding with your code to get the current user. If the current user is null, it indicates that the user is not logged in and you need to query the API for the data. In such cases, you should execute the code inside a promise.

Since the logic for handling both scenarios (user logged in / not logged in) is the same, it is recommended to move this code into a service for reusability.

Additionally, it is advisable to broadcast events each time the user logs in or out. This allows different parts of the application to listen to these events and react accordingly based on the information received.

When there is an infinite loop in the run block, the $http success callback in the factory is not triggered

Answer №1

Answer №2

Answer №3

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