How to use ValidationMessages properties file with parameters in Spring Boot?

Question

I am using Spring Boot validation to validate some fields.

I've created the ValidationMessages.properties file under resources and overwritten the value for the default validation of Size as follows:

javax.validation.constraints.Size.message=Please enter a value. Maximum length is {max}.

Which works like a charm, at runtime the {max} token is replaced with the value from the annotation @Size(max = 100) .

---

Now I want to define a custom proprietary entry, something like:

my.custom.message=Hey, my custom value is {customValue}

The question is - how can I replace the {customValue} token at runtime starting from something like?

private static final String CUSTOM_STRING = "{my.custom.message}";

Answer 1

In the context of validation, you must use something like:

@Documented
@Constraint(validatedBy = MyValidator.class)
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
public @interface MyAnnotation
{

    int customValue() default "THIS IS CUSTOM"; // this will be the value that will be injected in the custom message,
                                                // and can be changed when using the annotation

    String message() default "{my.custom.message}";

    Class<?>[] groups() default {};

    Class<? extends Payload>[] payload() default {};

}

Also, if you use private static final String CUSTOM_STRING = "{my.custom.message}"; in the context of validation, the replacement will be done.