How do I update RestTemplate to correctly map Java Dates?

Question

I have an issue where my RestTemplate.postForEntity(url, restRequest, RepoResponse.class) call is failing because it can't deserialise dates of the form:

• 2019-02-01T12:00:00.000-0500

because of the missing colon in the timezone.

Based on this answer, it looks like I want to change the date formatting of my RestTemplate's ObjectMapper.

I've tried a solution here: https://stackoverflow.com/a/38286322/14250

Which gives me the following code:

restTemplate = new RestTemplate();
ObjectMapper objectMapper = new ObjectMapper();
SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSS[XXX][X]");
objectMapper.setDateFormat(format);

MappingJackson2HttpMessageConverter messageConverter = new MappingJackson2HttpMessageConverter();
messageConverter.setPrettyPrint(false);
messageConverter.setObjectMapper(objectMapper);
restTemplate.getMessageConverters().removeIf(m->m.getClass().getName().equals(MappingJackson2HttpMessageConverter.class.getName()));
restTemplate.getMessageConverters().add(messageConverter);

Unfortunately I get the following error

com.fasterxml.jackson.databind.exc.InvalidDefinitionException: Cannot construct instance of `java.time.OffsetDateTime` (no Creators, like default construct, exist): no String-argument constructor/factory method to deserialize from String value ('2019-02-13T12:33:19.179-0500')

Is there an easy way to make RestTemplate support the above datetime format?

Answer 1

When you are working with java.time.* classes and Jackson is good to start from registering JavaTimeModule which comes from jackson-datatype-jsr310 module.

import com.fasterxml.jackson.annotation.JsonFormat;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.datatype.jsr310.JavaTimeModule;

import java.time.OffsetDateTime;

public class JsonApp {

    public static void main(String[] args) throws Exception {
        JavaTimeModule javaTimeModule = new JavaTimeModule();

        ObjectMapper mapper = new ObjectMapper();
        mapper.registerModule(javaTimeModule);

        String json = "{\"now\":\"2019-02-01T12:01:01.001-0500\"}";
        System.out.println(mapper.readValue(json, Time.class));
    }
}

class Time {

    @JsonFormat(pattern = "uuuu-MM-dd'T'HH:mm:ss.SSSX")
    private OffsetDateTime now = OffsetDateTime.now();

    public OffsetDateTime getNow() {
        return now;
    }

    public void setNow(OffsetDateTime now) {
        this.now = now;
    }

    @Override
    public String toString() {
        return "PrintObject{" +
                "now=" + now +
                '}';
    }
}

Above code prints:

PrintObject{now=2019-02-01T17:01:01.001Z}