Скачать или смотреть How to Raise Errors in WebFlux When an Array Length is Invalid

Learn how to effectively handle errors in WebFlux sequences by asserting the array length during the data processing. Explore methods to ensure data integrity with error handling techniques.
---
This video is based on the question https://stackoverflow.com/q/72104812/ asked by the user 'SledgeHammer' ( https://stackoverflow.com/u/5004822/ ) and on the answer https://stackoverflow.com/a/72105377/ provided by the user 'badger' ( https://stackoverflow.com/u/7838169/ ) 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: Raise error / assert in webflux sequence?

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.
---
How to Raise Errors in WebFlux When an Array Length is Invalid

In the world of reactive programming with Spring WebFlux, we often find ourselves managing sequences of data where conditions must be met to ensure the integrity of our processing. One common scenario is needing to validate the length of an array after performing an operation, such as splitting a string by a delimiter. But how can we appropriately raise an error when the array length does not meet our expectations? Let's dive into a clear and structured solution to this problem.

The Problem

Suppose you have a sequence of strings that you want to process by splitting them based on a comma delimiter. Your objective is to ensure that the resulting array has an exact number of items. For instance, if the requirement is to have three items in the array, any string that doesn’t fulfill this condition should trigger an error, redirecting the flow into an OnErrorResume() method for handling the exceptional case.

You may initially think about using the map operation to transform your strings into arrays, followed by a manual check for array length using a structure similar to:

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

However, this approach lacks elegance and could be improved. Instead, we can utilize built-in functionalities in WebFlux that align better with its reactive programming model.

The Solution: Using the handle Method

A more idiomatic approach to managing this conditional logic in WebFlux is to utilize the handle method. This method allows you to manipulate the emitted items and handle potential errors in a more streamlined way.

Step-by-Step Implementation

Here’s how you can apply the handle method for this situation:

Split the String: Continue splitting the string using the map function.

Handle the Logic: Use the handle function to perform your logic checks on the resultant array.

Throw an Error: If the condition fails (for example, if the array length is not equal to the expected x items), trigger an error using sink.error().

Here’s a code snippet demonstrating this solution:

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

Explanation of the Code

map: This function processes each string in the sequence, splitting them into an array.

handle: This is key to our solution. It allows us to assert the length of the array:

sink.next(arr) sends the array down the reactive stream if the length is as expected.

sink.error() raises an error if the length discrepancy exists, creating an ArrayLengthException that you can later handle with specificity.

onErrorResume: Finally, this method is invoked to manage the error gracefully, allowing you to emit a default value or to handle the situation as necessary.

Conclusion

Managing array lengths while processing data in Spring WebFlux does not need to complicate your codebase. By adopting the handle method effectively, you can maintain a clean, readable style while ensuring data integrity through proper error handling. This leads to better maintainability and aligns well with the reactive programming paradigm.

If you find yourself in need of clear error handling based on data conditions within your WebFlux applications, remember this approach as it promises both effectiveness and clarity.