How to Set Custom Field Names in Spring Boot Annotation Validation

Learn how to customize error messages in your Spring Boot applications by setting custom field names for validation annotations.
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How to Set Custom Field Names in Spring Boot Annotation Validation

When building REST applications with Spring Boot, effective validation mechanisms are crucial for ensuring data integrity. A common requirement is the ability to customize error messages. Specifically, many developers want to set custom field names in validation error messages for a better user experience. In this guide, we'll explore how to accomplish that using a simple example.

The Problem

In a Spring Boot application that handles JSON input, you might find yourself needing to validate fields within a data class. Let’s say you have a class for Contact that includes an email field. You want the validation error messages to reflect a custom name, such as "E-mail address", instead of just the field variable name (like "email").

Here's an example of what you might be starting with:

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In the above code, the default error message returns the variable name directly, which isn't user-friendly.

The Solution

Step 1: Create a FieldName Class

Instead of hardcoding field names directly in your error messages, a more reusable approach is to create a separate class that contains display names for your fields. This allows you to manage display names in a centralized location.

Here’s how to create the FieldName class:

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Step 2: Update the ErrorMessages Class

Next, modify the ErrorMessages class to append the field name from FieldName. By doing this, you can tailor your error messages without repeating yourself throughout the code.

Here’s the updated ErrorMessages class:

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Step 3: Update the Contact Class

Now, update the Contact class to utilize the new error message format for the email validation.

Here’s how your Contact class will look after this change:

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Expected Outcome

With these changes in place, when a JSON payload exceeds the defined length for the email field, the error response will look like this:

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

This provides a clear and user-friendly message that identifies the specific field in question, thereby enhancing the overall user experience of your application.

Conclusion

Customizing error messages in a Spring Boot application can significantly enhance error reporting and improve user experience. By following the steps outlined above, you can set custom field names in your validation annotations without hardcoding them in your error messages. This approach not only keeps your code cleaner but also allows for a more consistent handling of field names across your application.

You can use this method to implement similar functionality for other fields in your class, enhancing clarity in all of your validation error responses!

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