Fixing @ Size and @ NotEmpty Validation Issues in Spring MVC

Описание: Discover effective solutions to ensure that `@ Size` and `@ NotEmpty` annotations are working properly in your Spring MVC applications.
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This video is based on the question https://stackoverflow.com/q/76135151/ asked by the user 'Vlad Zherikhov' ( https://stackoverflow.com/u/21770498/ ) and on the answer https://stackoverflow.com/a/76381730/ provided by the user 'John Williams' ( https://stackoverflow.com/u/8041003/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Understanding Validation Issues in Spring MVC

When developing applications using Spring MVC, validation is a vital component that assures data integrity and improves user experience. However, you may encounter scenarios where validation annotations like @ Size and @ NotEmpty do not trigger as expected.

In this post, we'll discuss a common problem related to validation in Spring MVC applications and how to solve it effectively. We’ll guide you through identifying the issue, revising your code, and implementing a clean solution.

The Problem

Suppose you have created a simple user registration form and applied validations on certain fields, specifically firstName and secondName:

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Despite the implementation of these annotations, upon submitting the form, the validation does not seem to work as intended. This can be frustrating, especially when ensuring data validation is critical to your application's functionality.

Identifying the Cause

The primary reason for this issue lies in the annotation used for model validation in the controller. You may notice that @ Valid, a common annotation used in earlier versions of Spring, is not firing validation correctly in certain configurations of Spring 5 with Java 11.

For example, here’s the line in your controller that’s meant to trigger validation:

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While @ Valid works in some cases, switching to a different annotation is necessary to get it functioning correctly.

The Solution

Step 1: Replace @ Valid with @ Validated

To resolve the issue, you should replace @ Valid with @ Validated. The @ Validated annotation is specifically tailored to work with Spring, providing the expected validation functionality in these circumstances.

Here's how the modified method should look:

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Step 2: Ensure Proper Imports

Make sure to import the correct @ Validated annotation from the Spring framework:

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Benefits of Using @ Validated

Using the @ Validated annotation:

Compatibility: Ensures better compatibility with Spring 5 and above, especially when using Java 11 or similar configurations.

Specificity: Allows for clearer intent in the code regarding which validation framework you are utilizing.

Error Handling: Provides the necessary runtime checks that can help catch validation issues early on.

Conclusion

By replacing @ Valid with @ Validated, you enable the validation framework to effectively process and trigger any rules defined with annotations like @ Size and @ NotEmpty. This simple adjustment can save you from unnecessary debugging, ensuring that your Spring MVC application behaves as intended.

Summary of Steps:

Change @ Valid to @ Validated in your controller method.

Ensure the proper import statement for @ Validated.

Test your application to confirm that the validation errors are displayed correctly.

With this enhancement, you'll have a more robust validation process and a smoother user experience in your Spring MVC application.



Now, go ahead and implement these changes to ensure your application's data entries are validated correctly!