Скачать или смотреть How to Fix findAll() and findById() Returning Wrong Values in Spring Boot with Spring Data JPA

Struggling with Spring Data JPA's `findAll()` or `findById()` methods returning object references instead of actual values? Discover how to implement a custom `toString()` method to resolve this issue.
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This video is based on the question https://stackoverflow.com/q/63301674/ asked by the user 'Crossei' ( https://stackoverflow.com/u/10638846/ ) and on the answer https://stackoverflow.com/a/63301828/ provided by the user 'Łukasz Olszewski' ( https://stackoverflow.com/u/1151108/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Understanding the Problem: findAll() Returning Object References

If you're developing a Spring Boot application using Spring Data JPA and you've encountered an issue where the findAll() method (or even the findById() method) is returning object references instead of meaningful values, you're not alone. This is a common issue that can be frustrating, especially when you expect to see the contents of an entity being returned.

In the provided scenario, the findAll() method was called on a repository fetching a list of Alien objects from the database. However, the output was something like this:

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

Here, instead of meaningful Alien details, you only see the object references. Let’s take a closer look at how to solve this issue.

Solution: Implementing a Custom toString() Method

The default implementation of the toString() method in Java returns the class name followed by the object’s hash code in hexadecimal, which is exactly what you're seeing. To have your Alien entity return more useful information, you'll need to override this method in your entity class.

Steps to Override the toString() Method

Locate Your Entity Class: The entity class, in this case, is Alien.

Add the toString() Method: Implement a custom method that returns a formatted string containing the values of the entity's fields.

Here’s how you can do it:

Example Code:

Alien Entity Implementation:

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

Explanation of the Code:

Annotations: The @ Entity annotation indicates that this class is a JPA entity.

Fields: You have three fields: aid, name, and tech.

Custom toString() Method: This method constructs a string representation of the Alien instance, including all its fields. This will allow you to see meaningful details when you retrieve data from the database.

Conclusion

After implementing the above changes, when you call repo.findAll().toString(), instead of seeing object references, you should see a list of Alien details like this:

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

This approach not only enhances the readability of your output, but it also aids in debugging and logging efforts. In Spring Boot, always remember to implement meaningful toString() methods for your entity classes.

By following these practices, you will resolve the issue of findAll() and findById() returning unhelpful object references, thus improving your application's output significantly. If you have any further questions or encounter more issues, feel free to ask!