Скачать или смотреть Resolving kotlin.UninitializedPropertyAccessException in Spring Security with Kotlin

Learn how to fix the issue of field injection failure in a Spring Security application using Kotlin, specifically when implementing OAuth2 with a custom authentication success handler.
---
This video is based on the question https://stackoverflow.com/q/74198616/ asked by the user 'Ethan Michel' ( https://stackoverflow.com/u/16754666/ ) and on the answer https://stackoverflow.com/a/74228291/ provided by the user 'Ethan Michel' ( https://stackoverflow.com/u/16754666/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: Spring Security Kotlin Field Injection of Repository Class Failing

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Resolving kotlin.UninitializedPropertyAccessException in Spring Security with Kotlin

As a beginner in Spring and Kotlin, you might encounter various integration challenges while setting up security features in your application. One common issue many developers face is the failure of dependency injection within their classes, particularly when dealing with security configurations and custom authentication success handlers. In this guide, we’ll walk you through troubleshooting a specific problem related to field injection of the repository class in a Spring Security environment.

The Problem

In the scenario at hand, the user is trying to implement OAuth2 authentication along with a custom success handler in a Spring Security configuration. The handler is designed to store user details in a MongoDB database after successful authentication. However, an error arises when the injected repository (userRepository) is not initialized, leading to a kotlin.UninitializedPropertyAccessException.

This error typically occurs when a lateinit variable is accessed before being properly initialized, which in this case is due to the improper handling of the authenticationSuccessHandler instance in the security configuration.

Here's a breakdown of the issue:

Context: The AuthenticationSuccessHandler class has a userRepository dependency injected using @Autowired.

Error: Upon attempting to save user details, you receive the error:

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

The Solution

To resolve this issue, you need to ensure that the Spring framework manages the AuthenticationSuccessHandler instance rather than creating a new instance of it manually within the configuration. Here’s how you can fix the problem step-by-step:

Step 1: Modify Security Configuration

Change the way you instantiate the AuthenticationSuccessHandler in the security configuration. Instead of creating a new instance with AuthenticationSuccessHandler(), use the one that you have already injected into the constructor of your security configuration.

Updated Code Snippet

Replace this line in your SecurityConfig:

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

With this line:

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

This change tells the Spring framework to use the already initialized authenticationSuccessHandler, which has the userRepository properly injected.

Step 2: Ensure Proper Injection

Make sure that your userRepository is correctly defined as a Spring component and is marked with the appropriate annotations (like @Repository), which allows it to be automatically detected and injected by Spring’s component scanning.

Example Repository Definition

Ensure your UserRepository looks something like this:

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

Step 3: Test the Implementation

After making these adjustments, test your application to ensure that upon a successful authentication event, the user details can be saved without throwing the uninitialized property exception.

Conclusion

By following these steps, you can successfully resolve the kotlin.UninitializedPropertyAccessException and ensure that your repository is injected properly and used in your Spring Security application with Kotlin. Dependency injection is a powerful feature in Spring, and understanding how to leverage it correctly will greatly enhance the robustness of your applications.

If you encounter further issues or have questions regarding Spring Security, feel free to ask in the comments below!