how to use validation service in my controller?

[lethal kraken]

hey guys. im looking for advice on this question. right now i have this:

 @PostMapping(value = "/myendpoint", produces = "application/json")
    @ResponseStatus(HttpStatus.CREATED)
    public ResponseEntity<PaymentDTO> createPaymentInformation(@RequestBody @Valid PaymentDTO paymentInformationRequest){
        myValidationService.validateCreatePaymentInformationRequest(paymentInformationRequest);

        PaymentDTO paymentInformationResponse=myService.createPaymentInformation(paymentInformationRequest);
        ResponseEntity<PaymentDTO> responseEntity = new ResponseEntity<>(paymentInformationResponse, HttpStatus.CREATED);
        return responseEntity;
    }

i need to manually check if some fields of my DTO are null. this is my myValidationService's method:

public void validateCreatePaymentInformationRequest(PaymentDTO paymentRequest){
        System.out.println("TransactionID: " + paymentRequest.getTransactionId());
        System.out.println("ClientID: " + paymentRequest.getClientId());
        System.out.println("Amount: " + paymentRequest.getAmount());
        System.out.println("Signature: " + paymentRequest.getSignature());
        //System.exit(1);

        if (paymentRequest.getAmount() == null) {
            //todo return 400 bad req
        }
        if (paymentRequest.getClientId() == null) {
            //todo return 400 bad req
        }

so my questions are:

1. should i craete try-catch block in my controller, and in try block call the validation method?
2. or can i leave the controller as is?
3. if amount or clientId is null, i want to return 400 bad request. do i need to create a custom exception that should be handled in my exception handler?

thanks for your help

[novel fern]

<@&1004656351647117403> please have a look, thanks.

[dusky moon]

Why do you have both that service, and @Valid on your DTO? That's a check one would normally place there.

[light plank]

I may be wrong, but i think you must either manually return back a 400 http response ( i think a java exception will return something like a 500 internal server error) or use the @Valid

[reef notch]

just annotate fields with jakarta's NotNull annotation and create controller advice which overrides handleMethodArgumentNotValid

no need to reinevent the wheel

it will return 400 and in the overridden method you can add info about what exactly is incorrect

this, of course, requires you to have hibernate-validator

[lethal kraken]

sorry, i didnt really understand what you mean

[lethal kraken]

sorry, i was thinking about it too, but i already mentioned this in my question: i need to manually check if some fields of my DTO are null 😦

[reef notch]

For which purpose?

[dusky moon]

Why not use the @NotNull annotation, I can't think of a good reason why you'd do this manually.

[reef notch]

I have a case where I could derive some of the fields of the request from the auth token, so they can actually be null in some cases, but not others. But if the validation is a simple check that should always be performed, just use annotations.

Otherwise, you can throw a ResponseStatusException, or a subtype of it, or any exception annotated with @ResponseStatus