Скачать или смотреть Understanding HTTP Codes for Null or Empty Uni/Multi in RESTEasy

Discover how HTTP codes behave in `RESTEasy` when returning possibly null or empty `Uni` or `Multi`. Learn best practices for handling these responses.
---
This video is based on the question https://stackoverflow.com/q/62613983/ asked by the user 'Obb' ( https://stackoverflow.com/u/7462177/ ) and on the answer https://stackoverflow.com/a/62640026/ provided by the user 'geoand' ( https://stackoverflow.com/u/2504224/ ) 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: What are http codes when returning possibly null Uni or empty Multi in reasteasy?

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.
---
Understanding HTTP Codes for Null or Empty Uni/Multi in RESTEasy

When developing REST APIs, handling responses that may contain no data is a vital aspect of providing a clean and efficient user experience. In the context of using RESTEasy with a reactive programming model like Mutiny, many developers encounter confusion around the appropriate HTTP status codes to use when returning a possibly null or empty Uni or Multi. This post will explore the behavior of HTTP codes in these situations and how to handle them correctly.

The Problem

As a developer using RESTEasy, you may wonder:

What HTTP status code should I return when a requested resource is potentially not found or has no content, specifically when dealing with Uni or Multi responses?

Is it appropriate to return a 204 No Content status, or should I opt for a 404 Not Found if the resource does not exist?

This question arises particularly when making GET requests, such as fetching user information from /users/123, where you may receive an empty response.

Standard Behavior of HTTP Codes

When working with APIs, it is essential to align with established HTTP standards. The behavior you've experienced when using RESTEasy should primarily follow the guidelines outlined in JAX-RS (Java API for RESTful Web Services), which underpins RESTEasy implementations. Here's a quick overview of relevant HTTP status codes:

Commonly Used HTTP Status Codes

204 No Content: Indicates that the server successfully processed the request but does not have any content to return. This status is useful when the resource exists, but there is no additional information to send back to the client.

404 Not Found: Indicates that the requested resource could not be found on the server. This should be used when the resource (like a user) does not exist.

Why Return 204 Instead of 404?

Returning a 204 No Content response suggests that you successfully processed the request but that the resource exists without context, effectively indicating that you acknowledged the presence of the resource structure but had no data within. This can cause confusion for consumers of your API who may not differentiate between "resource exists, but no data" and "resource does not exist."

However, you might prefer to return a 404 Not Found in scenarios like:

When querying an endpoint for a resource (like a user) that does not exist,

To maintain consistency and clear communication with clients, clarifying that the requested entity is simply not there.

How to Check Uni or Multi Before Returning Results

To manage these possible outcomes effectively, it’s essential to verify whether your Uni or Multi contains data before deciding on an HTTP response. Here’s a simple approach using Mutiny with RESTEasy:

For Uni

You can use the onItem method to check if the retrieved object is null:

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

For Multi

For handling Multi, you can utilize a similar approach, inspecting the influx of items:

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

Using this pattern helps you ensure your API communicates effectively, aligning HTTP status codes to the actual state of your resource.

Conclusion

In conclusion, understanding the appropriate HTTP codes to use when returning possibly null or empty Uni or Multi in RESTEasy is crucial for effective API design. Remember, opting for a 204 No Content response should be a deliberate choice based on your API's necessities. However, when clarity is key, especially concerning resource existence, leaning towards a 404 Not Found may be the better option.

By implementing checks on your returned Uni or Multi, you can enhance your API's reliability, ensuring that clients receive