Скачать или смотреть Handling NullReferenceException When Displaying User Profile Pictures in ASP.NET Core

Discover how to avoid the `NullReferenceException` in ASP.NET Core when displaying user profile pictures. We’ll guide you through safe checks to enhance your user experience.
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This video is based on the question https://stackoverflow.com/q/67219818/ asked by the user 'Johnny' ( https://stackoverflow.com/u/5848588/ ) and on the answer https://stackoverflow.com/a/67220104/ provided by the user 'Matthew M.' ( https://stackoverflow.com/u/814172/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Troubleshooting User Profile Picture Issues in ASP.NET Core

When developing an ASP.NET Core application, you might want to enhance your user experience by allowing users to add profile photos. However, implementing this feature might lead to unexpected issues, especially if you don't handle certain scenarios where a user has not uploaded a photo yet. A common error encountered in this context is the infamous NullReferenceException that may occur when trying to access properties of an object that might not exist. In this post, we will explore how to safely check for the user profile picture and ensure a smooth user experience during login.

The Problem: An Unhandled Exception

In your application, you have successfully integrated the feature of allowing users to upload their profile photos. The intention is to display this photo once the user logs in. But what happens when a user creates a new account without adding a profile picture? Upon attempting to log in, you may encounter a failure because the code does not gracefully handle the absence of the photo. The code snippet below illustrates the problem:

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

Encountered Error

During execution, when the code attempts to access ProfilePicture.Length, it triggers a NullReferenceException if the ProfilePicture is null, preventing the user from logging in entirely.

The Solution: Safely Checking for Null Values

To avoid the NullReferenceException, it's crucial to ensure that you check for null before accessing properties of an object. Let's revise the code to ensure it handles cases where a profile picture is not present.

Step 1: Fix Your Condition

Change your checking condition to check for null first before checking the length. The corrected code would look like this:

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

Step 2: Utilize the Latest Syntax (Optional)

If you're using a recent version of C# and Razor, you can make the code even more resilient by employing the null-conditional operator ?.. This prevents exceptions if any part of the chain is null:

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

Conclusion

By implementing these checks, you can gracefully handle scenarios where a user hasn't uploaded a profile picture, significantly enhancing user experience. Errors like NullReferenceException can be frustrating, but with careful handling of null values, we can ensure that feature implementations behave as expected without causing disruptions.

Now, your users can enjoy a seamless login experience, with or without a profile picture! Keep improving your ASP.NET Core applications by prioritizing error handling and providing a smooth user interface. Happy coding!