How to Fix Angular AuthGuard's Redirection Issue

Learn how to troubleshoot and fix the Angular AuthGuard redirection issue that prevents access to specific routes when returning true.
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This video is based on the question https://stackoverflow.com/q/66509859/ asked by the user 'Szyszka947' ( https://stackoverflow.com/u/14329228/ ) and on the answer https://stackoverflow.com/a/66510019/ provided by the user 'Tahsin Gül' ( https://stackoverflow.com/u/6205166/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Introduction

Angular's AuthGuard is a powerful feature used to control access to specific routes in your application. However, developers sometimes encounter an unwanted behavior where, despite fulfilling the guard's conditions and returning true, the user is redirected away from the desired route. In this guide, we'll investigate a common issue where returning true leads to an unexpected redirection and provide a precise solution.

Understanding the Problem

The problem arises in scenarios where an AuthGuard checks for token existence and authentication status but fails to return the expected boolean value appropriately. Specifically, the code provided by the user indicated that they were receiving console logs (like “test”), yet the routing behavior redirected them to the base path / instead of the intended route.

Our user encountered this issue in an implementation, as seen in their RouterModule setup and AuthGuard logic.

The Setup

Here's a glimpse of the route definitions in app.module.ts:

[[See Video to Reveal this Text or Code Snippet]]

And, the AuthGuard implementation triggered confusion:

[[See Video to Reveal this Text or Code Snippet]]

The Core Issue

The main issue lies in the asynchronous nature of the authentication check inside the canActivate method. When the guard executes the subscription to isAuthenticated, it doesn’t return the observable or boolean in a way that allows Angular's router to understand the outcome of the authentication check. As a result, users experience unexpected redirections, as Angular doesn't wait for the subscription to resolve.

Detailed Solution

To fix the redirection problem, we need to ensure that the decision made by the AuthGuard is returned correctly to the Router.

The Revised Code

The suggested solution involves modifying the canActivate method to return the observable directly instead of just handling it within the subscription. Here's how the revised code looks:

[[See Video to Reveal this Text or Code Snippet]]

Breakdown of Changes

Return the observable: Instead of subscribing directly, we use pipe and map to transform the authentication results.

Directly handle navigation: The navigation logic is preserved within the observable pipeline, ensuring that the router awaits the completion of the authentication status check.

Use of 'pipe': This approach keeps the code clean and allows the router to await the necessary boolean before deciding the route action.

Conclusion

By implementing the changes outlined above, you can mitigate the redirection problem and ensure users gain access to protected routes seamlessly. Angular’s AuthGuard is a robust tool for managing access, and understanding its async nature is key to leveraging its full potential. If you encounter similar issues, consider returning observables properly as demonstrated.

Remember, resolving such issues not only improves user experience but also solidifies your application's stability and reliability. Happy coding!

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