How to custom convert String to enum in @RequestBody?

Question

I want to send a JSON request body where fields can be enum values. These enum values are in camelCase, but the enum values are UPPER_SNAKE_CASE.

Kotlin classes:

data class CreatePersonDto @JsonCreator constructor (
        @JsonProperty("firstName") val firstName: String,
        @JsonProperty("lastName") val lastName: String,
        @JsonProperty("idType") val idType: IdType
)

enum class IdType {
    DRIVING_LICENCE,
    ID_CARD,
    PASSPORT;
}

My endpoint signature:

@PostMapping
fun createPerson(@RequestBody person: CreatePersonDto)

HTTP request:

curl -d '{ "firstName": "King", "lastName": "Leonidas", "idType": "drivingLicence" }' -H "Content-Type: application/json" -X POST http://localhost:8080/person

I want to convert "drivingLicence" to DRIVING_LICENCE implicitly.

I have tried:

• org.springframework.core.convert.converter.Converter: It works for @RequestParam, but not for @RequestBody
• org.springframework.format.Formatter: I registered this formatter, but when I make the request the parse() method is not executed.

My configuration so far:

@Configuration
class WebConfig : WebMvcConfigurer {

    override fun addFormatters(registry: FormatterRegistry) {
        registry.addConverter(IdTypeConverter())
        registry.addFormatter(IdTypeFormatter())
    }
}

Answer 1

You can try to use JsonProperty on enum directly

enum IdType {

    @JsonProperty("drivingLicence")
    DRIVING_LICENCE,

    @JsonProperty("idCard")
    ID_CARD,

    @JsonProperty("passport")
    PASSPORT;
}

If you want to have multimapping the simple thing would be defining mapping and using JsonCreator on enum level:

enum IdType {

    DRIVING_LICENCE,
    ID_CARD,
    PASSPORT;

    private static Map<String, IdType> mapping = new HashMap<>();

    static {
        mapping.put("drivingLicence", DRIVING_LICENCE);
        mapping.put(DRIVING_LICENCE.name(), DRIVING_LICENCE);
        // ...
    }

    @JsonCreator
    public static IdType fromString(String value) {
        return mapping.get(value);
    }
}

See also:

• Deserializing an enum with Jackson