VavrExample

gistfile1.txt

	private static final Logger LOGGER = LoggerFactory.getLogger(BoostResource.class);
	private final SomethingCommandHandler handler;
	
	@Autowired
	public SomeResource(SomethingCommandHandler handler) {
		this.handler = handler;
	}
	
	@RequestMapping(value = "/api", method = RequestMethod.POST)
	public ResponseEntity<Object> api(@RequestBody RequestValues request) {
		LOGGER.info("Boost called with request: {}", request);
		SomethingCommand operation = createCommand(request);
	
		Try<Object> operationTry = handler.perform(operation)
			.onSuccess(r -> LOGGER.info("Success"))
			.onFailure(e -> LOGGER.error("Failure", e));
	
		return Match(operationTry).of(
			Case($Success($()), o -> ResponseEntity.ok(o)),
			Case($Failure($()), e -> ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR).build())
		);
	}
	
	/**
	* Validate and create API operation parameter object.
	*
	* @param request parsed from http request.
	* @return SomethingCommand operation parameter object.
	* @throws InvalidOperationException if operation could not be validated.
	*/
	private SomethingCommand createCommand(RequestValues request) {
		Consumer<List<RequestValue>> warnIfEmpty = elements -> {
			if (elements.isEmpty()) {
				LOGGER.warn("No values found in API call.");
			}
		};
	
		CheckedFunction0<List<RequestValue>> values = () -> List.ofAll(request.getValues());
		CheckedFunction1<List<RequestValue>, RequestValue> findFirst = elements -> elements.get(0);
		CheckedFunction1<RequestValue, SomethingCommand> SomethingCommand = SomethingCommandMapper::toOp;
	
		return Try.of(values)
			.peek(warnIfEmpty)
			.mapTry(findFirst)
			.mapTry(SomethingCommand)
			.toOption()
			.getOrElseThrow(InvalidOperationException::new);
	}