Why do I get random Http 404 from server between same requests with only one change in any field? - spring

Question

I haven an endpoint POST /api/marketplace/add that accepts a DTO object as request body. When I send the body below with platformName field set , server accepts request and processes it with no problem. But when I only try to change field platformName to null I get Http 404 error from server. I debugged the request and found out that it even can not reach controller method. I also got no trace from that error. What might be the cause that makes API respond differently to same request?
below
{
"platformName": "Trendyol",
"commissionAmounts": [
{
"amount": 23.45,
"categoryInfos": [
{
"categoryName": "Game"
}
],
"isCategoryBasedPricing": true
}
],
"shipmentAmounts": [
{
"amount": 23.45,
"scaleInfo": {
"order": 0,
"lowerBound": 0,
"upperBound": 0
},
"volumeInfo": {
"order": 0,
"lowerBound": 0,
"upperBound": 0
},
"isVolumeBasedPricing": true
}]
}
EDIT: dto model is
#Generated
public class MarketPlaceDTO {
#JsonProperty("platformName")
private String platformName;
#JsonProperty("commissionAmounts")
#Valid
private List<CommissionInfoDTO> commissionAmounts = new ArrayList<>();
#JsonProperty("shipmentAmounts")
#Valid
private List<ShipmentInfoDTO> shipmentAmounts = new ArrayList<>();
Controller is implementing swagger generated api interface. with postmapping and requestbody annotations.
#RequiredArgsConstructor
#RestController
public class MarketPlaceApiController implements MarketplaceApi {
private final MarketPlaceDAOService marketPlaceDAOService;
#Override
public ResponseEntity<BaseResponseDTO> addMarketPlace(MarketPlaceDTO
marketPlaceDTO) {
BaseResponseDTO dto =
marketPlaceDAOService.addMarketPlace(marketPlaceDTO);
return ResponseEntity.ok(dto);
}
}
Swagger generated api interface
#RequestMapping(
method = RequestMethod.POST,
value = "/marketplace/add",
produces = { "application/json", "application/xml" },
consumes = { "application/json" })
default ResponseEntity<BaseResponseDTO> _addMarketPlace(
#Parameter(name = "MarketPlaceDTO", description = "Add new
marketplace with given request body", required = true) #Valid
#RequestBody MarketPlaceDTO marketPlaceDTO) {
return addMarketPlace(marketPlaceDTO);
}
Response is
{
"timestamp": 1666866382906,
"status": 404,
"error": "Not Found",
"path": "/marketplace/add"
}

Answer 1

Obviously, that you use an endpoint with #RequestBody where body is a DTO.
And on trying to call this endpoint Spring Web first should match that a model in your request payload matches a require object in #RequestBody argument.
Ideally, using DTO as a request model is not a good idea. But I don't see your structure and cannot say if it's a problem or not.
The simple solution in your case is preparation (annotating) your DTO with specific JSON annotations:
#JsonInclude
#JsonIgnoreProperties(ignoreUnknown = true)
public class YourDTO {
private String platformName;
}
and for Controller add class annotation #Validated; for #RequestBody add #Valid annotation.
Recommendation: use request models for incoming objects, and later converters to DTO/entities with ability to response them with filtering (or in complex cases add also response model - usually it's overhead).

Answer 2

My problem was global exception handler component annotated with #ControllerAdvice. I tried to handle validation exceptions and forgot to add #ResponseBody to my handler methods which is in my case probabaly required. That somehow caused server to send http 404 message when any input validation exception was thrown. After I made changes , Exceptions was handled correctly by handler component.
#ControllerAdvice
#ResponseBody // this resolved my issue.
public class MVCExceptionHandler {
#ExceptionHandler(MethodArgumentNotValidException.class)
#ResponseStatus(HttpStatus.BAD_REQUEST)
public BaseErrorResponse
methodArgumentExceptions(MethodArgumentNotValidException e){
return BaseErrorResponse.builder()
.errorMessage(AppError.INVALID_OR_MISSING_USER_INPUT.getErrorMessage())
.errorCode(AppError.INVALID_OR_MISSING_USER_INPUT.getErrorCode())
.errorTime(Date.from(Instant.now())).build();
}