Filtering and default value in Reactor-CodePudding

I'm presently experiencing a really strange and frustrating issue at the moment. I have some code that is being tested that runs through a reactive call chain containing a series of filtering operations.

As the test runs through the code and a 'false' value is returned, the code still passes through to the next call in the chain instead of just returning.

Since I'm still a 'reactive newbie' I'm figuring I'm probably not doing something incorrectly here in the reactive code chain.

Here is the code:

    private Mono<GetCardNumberServiceResponseData> updateCardNumberIfLastFourValidAndShaIsNull(Card card, GetCardNumberServiceResponseData responseData) {
        return Mono.just(responseData)
            .filter(response -> isValidLastFour(card, response))
            .defaultIfEmpty(responseData)
            .filter(response -> shaIsNull(card))
            .defaultIfEmpty(responseData)
            .flatMap(response -> updateCardNumber(card, response));
    }

This is the portion that's not evaluating correctly:

.filter(response -> isValidLastFour(card, response))

This is what 'isValidLastFour' currently looks like:

    private boolean isValidLastFour(Card card, GetCardNumberServiceResponseData responseData) {
//      String cardNumberFromResponse = responseData.getCardNumber();
//      String lastFourFromResponse =
//          cardNumberFromResponse.substring(cardNumberFromResponse.length() - 4);
//      return card.getLastFour().equals(lastFourFromResponse);
        return false;
    }

So presently I just have it hard-coded to return 'false', but as I step through the test with the debugger, the execution just passes right through as if 'true' is being returned, so I'm really just at a loss at what might be causing this behavior.

As always, any and all help is always greatly appreciated!

CodePudding user response：

If you want responseData to be the default value, in case there is an empty Mono, you have to put defaultIfEmpty at the end of the chain:

 return Mono.just(responseData)
        .filter(response -> isValidLastFour(card, response))
        .filter(response -> shaIsNull(card))
        .flatMap(response -> updateCardNumber(card, response))
        .defaultIfEmpty(responseData);

Even better, you can merge those filters:

 return Mono.just(responseData)
        .filter(response -> isValidLastFour(card, response) && shaIsNull(card))
        .flatMap(response -> updateCardNumber(card, response))
        .defaultIfEmpty(responseData);