Resolving the Field of Array Issue in Spring Boot 3 Open API Responses

Learn how to fix the `Field of array` rendering issue in your Spring Boot 3 application using Springdoc Open API, ensuring accurate API documentation and response structure.
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Resolving the Field of Array Issue in Spring Boot 3 Open API Responses

When working with Spring Boot 3 and Springdoc Open API, you may encounter issues with how fields in your response class are represented. This guide explores a common problem where an array field in the response class does not get rendered correctly. Here, we will dive into the details of the problem and present a solution to ensure your API documentation and responses are accurate.

The Problem

You might have noticed that your returned JSON structure doesn't align with expectations. Specifically, with the example of a UserResponse entity which includes a list of scores, sometimes the expected structure fails to render with the proper data types and formats.

Example Problem Setup

Here's a recap of the response classes defined:

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The Expectations vs. Reality

Expected Output in Swagger UI:

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Actual Output:

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The actual output indicates that while the other properties render accurately, the score field returns a list of strings instead of a list of Score objects, which is not what you intended.

The Solution

After researching the problem, it became apparent that the reference to the schema was breaking, leading Spring to ignore the array definition. Fortunately, there is a simple configuration change that can resolve this issue.

Configuration Steps

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This property alteration instructs Springdoc to retain references in the Open API schema, preventing reference removal that leads to rendering errors.

Implementing a Custom Open API Schema

In addition to the configuration fix, you might also consider implementing a custom Open API schema bean in your handler class, like so:

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

This OpenApiCustomizer ensures that all your schemas are resolved correctly, maintaining their references throughout the Open API documentation.

Conclusion

Be sure to utilize these practices not only to troubleshoot existing issues but also as a preventive measure for future projects involving Spring Boot and Open API. With thorough comprehension and application, you can maintain a robust and reliable API.

If you found this blog helpful, don’t hesitate to share it with others who might face similar issues!