how to properly handle case when theres no records in the db table?

[unborn swan]

hey guys. so i have my CustomerRepo in my service and i want to handle a scenario when there are no customers with given id. so far i have this:

Optional<Customer> customer=customerRepository.findById(Long.valueOf(paymentInformationRequest.getClientId()));
        if (customer.isEmpty()) {
            log.info("BGWService.createPaymentInformation. no customer with id: {}", paymentInformationRequest.getClientId());
            throw new IllegalArgumentException("BGWService.createPaymentInformation. no customer with id:"+paymentInformationRequest.getClientId());
        }

but i was wondering if i can do smth better? thx

[coral night]

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[shy cave]

use .orElseThrow on optional to throw an exception

Preferably an exception you define yourself that means that a customer isn't found

CustomerNotFoundException or something similar. This you can catch in a @ControllerAdvice

And then do the logging there

[unborn swan]

u mean smth like this?

@ControllerAdvice
public class RestResponseEntityExceptionHandler extends ResponseEntityExceptionHandler {
    @ExceptionHandler(value={IllegalArgumentException.class, IllegalStateException.class})
    protected ResponseEntity<Object> handleConflict(RuntimeException runtimeException, WebRequest webRequest) {
        String bodyOfResponse = "This should be application specific";
        return handleExceptionInternal(runtimeException, bodyOfResponse,new HttpHeaders(), HttpStatus.CONFLICT, webRequest);
    }
}

[shy cave]

It's been a while, I'd have to look all that up, but yeah, something along those lines

But don't do it for IllegalArgument or IllegalState

Make your own exceptions so you have a clear definition of what went wrong

[unborn swan]

i have :

@ControllerAdvice
@Slf4j
public class RestResponseEntityExceptionHandler extends ResponseEntityExceptionHandler {
    @ExceptionHandler(value={IllegalArgumentException.class})

    protected ResponseEntity<Object> handleNoCustomerException(RuntimeException runtimeException, WebRequest webRequest) {
        //todo write custom exception when client doesnt exist

        log.info("BGWService.createPaymentpaymentConfirmation. NoCustomerException");

        String responseBody = "Customer with id"+;
        return handleExceptionInternal(runtimeException, responseBody,new HttpHeaders(), HttpStatus.CONFLICT, webRequest);
    }
}

and i have a question. how to pass argument to this contoller advice? can i pass it when throwing an exception?

[shy cave]

Yes, with a custom exception you can have as many arguments as you want

[coral night]

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[unborn swan]

but how do i know if i need checked or unchecked exception?

[shy cave]

That's up to you. There's merit in both

[unborn swan]

but i dont even understand how they work and whats the difference

the more i read the less i understand

[shy cave]

Checked exceptions you have to either catch or declare explicitly (think IOException). Unchecked you don't (think IllegalArgumentException)

[unborn swan]

yes, i read that too, but it still doesnt explain a thing

[shy cave]

That's the difference

[unborn swan]

?

[shy cave]

That's literally the difference between the two

Nothing more I can explain

You can ask a new question so other people can help. I'm sure plenty of people have opinions on when to use one or the other

[unborn swan]

then maybe you can explain how to pass arguments to my custom exception? i have this so far:

            throw new NoCustomerException("BGWService.createPaymentInformation. no customer with id:"+paymentInformationRequest.getClientId());

``` but idk how to pass arguments

[shy cave]

An exception is just a class, so you can add fields and constructor parameters

[unborn swan]

so i added another field:

public class NoCustomerException extends Exception {
    public NoCustomerException(String message, String clientId ) {
        super(message);
    }
}

an i use it like this:

 throw new NoCustomerException("BGWService.createPaymentInformation. no customer with id:"+paymentInformationRequest.getClientId(),paymentInformationRequest.getClientId());

but how to access the clientId here?

@ControllerAdvice
@Slf4j
public class RestResponseEntityExceptionHandler extends ResponseEntityExceptionHandler {
    @ExceptionHandler(value={NoCustomerException.class})
    protected ResponseEntity<Object> handleNoCustomerException(RuntimeException runtimeException, WebRequest webRequest) {
        log.info("BGWService.createPaymentpaymentConfirmation. NoCustomerException");

        String responseBody = "Customer with id"+;
        return handleExceptionInternal(runtimeException, responseBody,new HttpHeaders(), HttpStatus.CONFLICT, webRequest);
    }

}

[shy cave]

Use the right exception as the parameter to that method