JSON decoding error: Cannot deserialize value of type `java.math.BigInteger` from Object value (token `JsonToken.START_OBJECT`); (Jackson) - spring-boot

Question

It is necessary to deserialize the result from Mono<ResultSumDto> to JSON, then to sent to the client as JSON.
Controller
#GetMapping("v1/sequence/{startRange}/{endRange}")
Mono<ResultSumDto > getSumFromRange(
#PathVariable BigInteger startRange,
#PathVariable BigInteger endRange) {
ResultSumDto resultSumDto = ...
return Mono.just(resultSumDto);
}
#Configuration
public class JacksonObjectMapperConfiguration {
#Autowired
public void serializeBigInteger(ObjectMapper objectMapper) {
JsonFormat.Value formatValue =
JsonFormat.Value.forShape(JsonFormat.Shape.STRING);
objectMapper
.configOverride(BigInteger.class)
.setFormat(formatValue);
}
}
#Data
#Builder
public class ResultSumDto {
private final BigInteger sumSeq;
private final BigInteger [] seqRange;
private final Boolean isCached;
}
private Mono<ResultSumDto> buildResult(SeqDto dto) {
Mono<BigInteger> sumSeq =
calculateSumRangeValuesFibonacciSequence(dto);
BigInteger bigInteger = null;
try {
bigInteger = sumSeq
.toFuture()
.get();
} catch (InterruptedException | ExecutionException e) {
log.error(e.getLocalizedMessage());
Thread.currentThread().interrupt();
}
BigInteger[] rangeGiven = new BigInteger[]
{dto.getStartRange(), dto.getEndRange()};
return Mono.just(ResultSumSeqDto.builder()
.sumSequence(bigInteger)
.sequenceRange(rangeGiven)
.isCached(false)
.build()
);
}
But I have a mistake:
org.springframework.core.codec.DecodingException: JSON decoding error: Cannot deserialize value of type java.math.BigInteger from Object value (token JsonToken.START_OBJECT); nested exception is com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot deserialize value of type java.math.BigInteger from Object value (token JsonToken.START_OBJECT)
at [Source: (io.netty.buffer.ByteBufInputStream); line: 1, column: 1]
But after all, when I get values in endpoint, serialization to the BigInteger type goes without problems.
Who has any idea why it doesn't work and how it can be fixed. Share your knowledge on how to deserialize an array BigInteger and a field with the BigInteger type?

Answer 1

That's what worked in my case.
public class DeserializeResultCalculateSumSequence
extends StdDeserializer<ResultCalculateSumSequenceDto> {
public DeserializeResultCalculateSumSequence() {
this(null);
}
protected DeserializeResultCalculateSumSequence(Class<?> vc) {
super(vc);
}
#Override
public ResultCalculateSumSequenceDto deserialize(JsonParser jsonParser,
DeserializationContext deserializationContext)
throws IOException, JacksonException {
JsonNode node = jsonParser
.getCodec()
.readTree(jsonParser);
BigInteger sumSequence = node
.get("sumSequence")
.bigIntegerValue();
ObjectMapper mapper = new ObjectMapper();
String sequenceRangeStr = node.get("sequenceRange").toString();
BigInteger[] sequenceRange = mapper
.readValue(sequenceRangeStr, BigInteger[].class);
boolean isCached = node
.get("isCached")
.asBoolean();
return ResultCalculateSumSequenceDto
.builder()
.sumSequence(sumSequence)
.sequenceRange(sequenceRange)
.isCached(isCached)
.build();
}
}
#Data
#Builder
#JsonDeserialize(using = DeserializeResultCalculateSumSequence.class)
public class ResultCalculateSumSequenceDto {
private final BigInteger sumSequence;
private final BigInteger [] sequenceRange;
private final Boolean isCached;
}