LocalDate is serialized as an array

Question

I'm using springBoot to develop a REST APi. And i have a LocalDate field "firstDate" in the response model of a GET endpoint. But this LocalDate is serializable as an array in the response's json!

"firstDate": [
        2021,
        3,
        1
      ],

So for consuming this APi, i have to define this date in my DTO as an array! which is not good! My reponse models of th API are generated with swagger so i can not use @JsonFormat(pattern="yyyy-MM-dd")

Can you help me please and tell me how to serialize LocalDate properly in this case ?

Thank you very much.

Answer 1

My dates defined as LocalDateTime were been serializaded as an array like this:

"timestamp": [
    2023,
    2,
    15,
    10,
    30,
    45,
    732425200
],

So here is what I did in my WebConfig.java:

@Configuration
@EnableWebMvc
public class WebConfig implements WebMvcConfigurer {

  // other configs

  @Override
  public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
    WebMvcConfigurer.super.extendMessageConverters(converters);
    converters.add(new MappingJackson2HttpMessageConverter(
        new Jackson2ObjectMapperBuilder()
            .dateFormat(new StdDateFormat())
            .featuresToDisable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS)
            .build()));
  }

}

Now everything is good again:

"timestamp": "2023-02-15T10:32:06.5170689",

Hope it's been helpful. Some topics that helped me achieve that:

Configure LocaldateTime in Spring Rest API

How to customise the Jackson JSON mapper implicitly used by Spring Boot?

Can't serialize java.time.LocalDate as a String with Jackson

Answer 2

I think this WebConfig.class is unnecessary. You could try something like that in your field firstDate:

@JsonFormat(shape = JsonFormat.Shape.STRING, pattern = "yyyy-MM-dd")
private LocalDate firstDate;

There's no make sense define the field as an array in DTO because of the swagger config