Cannot deserialize value of type LocalDateTime from String

Question

I have the following DTO and Entity:

public class PaymentDto {

    private String provider;

    private Duration timeDifferenceDate;

    public PaymentDto() {
        // Empty for framework
    }

    public PaymentDto(Payment payment) {
        this.provider = payment.getProvider();
        this.setRegistrationDate(payment.getRegistrationDate());
    }

    public Duration getRegistrationDate() {
        return timeDifferenceDate;
    }

    public void setRegistrationDate(LocalDateTime registrationDate) {
        LocalDateTime now = LocalDateTime.now();
        Duration duration = Duration.between(now, registrationDate);
        this.timeDifferenceDate = duration;
    }

}

public class Payment {

    private LocalDateTime registrationDate;

    public Payment() {
        // Empty for framework
    }

But when it converts from Payment to PaymentDto I have problems with JSON decoding, specifically with the conversion from LocalDateTime to Duration. Some idea?

    @Override
    public List<PaymentDto> readAll() {
        return this.paymentPersistence.readAll().stream()
                .map(PaymentDto::new).collect(Collectors.toList());
    }

org.springframework.core.codec.DecodingException: JSON decoding error: Cannot deserialize value of type `java.time.LocalDateTime` from String "PT-1.015005S": Failed to deserialize java.time.LocalDateTime: (java.time.format.DateTimeParseException) Text 'PT-1.015005S' could not be parsed at index 0; nested exception is com.fasterxml.jackson.databind.exc.InvalidFormatException: Cannot deserialize value of type `java.time.LocalDateTime` from String "PT-1.015005S": Failed to deserialize java.time.LocalDateTime: (java.time.format.DateTimeParseException) Text 'PT-1.015005S' could not be parsed at index 0
 at [Source: UNKNOWN; line: -1, column: -1] (through reference chain: com.user.rest.dtos.PaymentDto["registrationDate"])

    at org.springframework.http.codec.json.AbstractJackson2Decoder.processException(AbstractJackson2Decoder.java:215)
    Suppressed: reactor.core.publisher.FluxOnAssembly$OnAssemblyException: 
Error has been observed at the following site(s):
    |_ checkpoint ⇢ Body from GET http://localhost:61072/payments [DefaultClientResponse]
Stack trace:
        at org.springframework.http.codec.json.AbstractJackson2Decoder.processException(AbstractJackson2Decoder.java:215)

Thanks by the way. ;)

Answer 1

LocalDateTime can not be converted to Duration and vice versa. There is nothing common, except Serializable (and of course Object), in their hierarchies.

Replace

private LocalDateTime registrationDate;

with

private Duration registrationDate;

or create a new instance variable of type, Duration.

Answer 2

As @Arvind Kumar Avinash mentioned above, you need to provide appropriate type Duration in the setter PaymentDto::setRegistrationDate.

Also you should modify the "conversion" constructor if you populate a DTO from an entity which returns a LocalDateTime field. Also, when calculating the duration, you should place registrationDate first to avoid "negative" duration (earlier instant in time comes first).

public PaymentDto(Payment payment) {
    this.provider = payment.getProvider();
    this.setRegistrationDate(Duration.between(
        payment.getRegistrationDate(),  // older "start" date should go first
        LocalDateTime.now()
    ));
}

public void setRegistrationDate(Duration timeDifference) 
    this.timeDifferenceDate = timeDifference;
}