Spring Boot request body validation

I am working on Spring REST API and have following controller:

@RestController
@RequestMapping(
        value = "/api/Test",
        produces = "application/json"
)
public class MyController {

    @RequestMapping(method = RequestMethod.POST)
    public Response serviceRequest(@Valid @RequestBody ServiceRequest myServiceRequest)  {    
             ....    
    }
}

ServiceRequest has following structure:

@Getter
@Setter
@AllArgsConstructor
@NoArgsConstructor
public class ServiceRequest {

    @NotBlank
    private LocalDate fromDate;

    @NotBlank
    private LocalDate toDate;

}

My task is to introduce validation based on combination of fromDate and toDate field's values: if time period between them is longer that 1 week then validation should fail.

What is the best way to archive this please?

Solution

You may create a custom constraint validator that will validate the required conditions before processing the request.

DatesDifference.java

@Constraint(validatedBy = DatesDifferenceValidator.class)
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
public @interface DatesDifference {
    String message() default "Dates difference is more than a week";
    Class<?>[] groups() default { };
    Class<? extends Payload>[] payload() default { };
}

DatesDifferenceValidator.java

@Component
public class DatesDifferenceValidator implements ConstraintValidator<DatesDifference, ServiceRequest> {
    
    @Override
    public boolean isValid(ServiceRequest serviceRequest, ConstraintValidatorContext context) {
        System.out.println("validation...");
        if (!(serviceRequest instanceof ServiceRequest)) {
            throw new IllegalArgumentException("@DatesDifference only applies to ServiceRequest");
        }
        LocalDate from = serviceRequest.getFromDate();
        LocalDate to = serviceRequest.getToDate();

        long daysBetween = ChronoUnit.DAYS.between(from, to);
        System.out.println("daysBetween "+daysBetween);
        return daysBetween <= 7;
    }
}

ServiceRequest.java

@Getter
@Setter
@AllArgsConstructor
@NoArgsConstructor
@DatesDifference
public class ServiceRequest {
    @NotBlank
    private LocalDate fromDate;

    @NotBlank
    private LocalDate toDate;
}