Spring Boot - Custom JSON Serialization

Question

I generally use mixins to perform custom serialization and deserialization when using Jackson Library. My RestController in Spring Boot app has methods similar to one listed below. I guess Spring Boot uses Jackson to serialize the VerifyAccountResponse into string. However this converts my calendar / date objects into a long value when they are converted to String. I am able to convert them into appropriate format by using custom serializer. However I am having to change the return type into an object after serialization. Is there a way to retain the same signature and add custom serializer to default serialization performed by Spring Boot.

@RequestMapping(value ="verifyAccount", method = RequestMethod.POST, produces=MediaType.APPLICATION_JSON_VALUE)
public ResponseEntity<VerifyAccountResponse> verifyAccount(@RequestBody VerifyAccountRequest request) {

    VerifyAccountResponse response = service.verifyAccount(request);

    return new ResponseEntity<VerifyAccountResponse>(response, HttpStatus.OK);
}

EDIT:

Updated the below based on the answers , but mixin doesn't seem to take effect -

@Bean
public Jackson2ObjectMapperBuilder objectMapperBuilder() {
    Jackson2ObjectMapperBuilder builder = new Jackson2ObjectMapperBuilder();

    builder.mixIn(ConnectStatus.class, com.datacast.service.util.DateFormatSerializerMixin.class);

    return builder;
}

EDIT 2:

I created a simple spring boot project to test this out and this works fine. But when I use this approach in my larger project , the date conversion is not happening. Could there be anything overriding Jackson2ObjectMapperBuilder ?

Solution 1

You can customize the Jackson serializer in a spring boot application in a lot of ways. Please consider checking the documentation regarding jackson in the spring boot reference guide:

https://docs.spring.io/spring-boot/docs/current-SNAPSHOT/reference/html/howto.html#howto-customize-the-jackson-objectmapper

You can configure a custom serializer by using Jackson2ObjectMapperBuilder.

http://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/http/converter/json/Jackson2ObjectMapperBuilder.html#serializerByType-java.lang.Class-com.fasterxml.jackson.databind.JsonSerializer-

Solution 2

You can customize date format (as I understand it's the main reason of your post) by setting property

spring.jackson.date-format= 
# Date format string or a fully-qualified date format class name.
For instance `yyyy-MM-dd HH:mm:ss`.

Comments

[Punter Vicky]

Thanks @dimuha. But I have multiple date fields each having different format.

[Punter Vicky]

Thanks @Lakatos. I updated the mixins but still doesn't take effect. I have updated the code in my original post.

[Punter Vicky]

I implemented this in a separate program and this works great. However when I used it in my app , it didn't return the formatted date. I am extending classes from few jars which are using EnableMvc annotation. I am suspecting this causing serialization from being performed.