Lombok 1.18.0 and Jackson 2.9.6 not working together

Question

The deserialization is failing after the update.

I updated my micro-service from Spring 1.5.10.RELEASE to Spring 2.0.3.RELEASE

Answer 1

Lombok stopped generating @ConstructorProperties on constructors with version 1.16.20 (see changelog), because it might break Java 9+ applications that use modules. That annotation contains the names of the constructor's parameters (they are removed when compiling the class, so that's a workaround so that the parameter names still can be retrieved at runtime). Because the annotation is now not being generated by default, Jackson cannot map the field names to the constructor parameters.

Solution 1: Use a @NoArgsConstructor and @Setter, but you will loose immutability (if that's important to you).

Update: Just @NoArgsConstructor and @Getter (without @Setter) may also work (because INFER_PROPERTY_MUTATORS=true). In this way, you can keep the class immutable, at least from regular (non-reflective) code.

Solution 2: Configure lombok to generate the annotations again, using a lombok.config file containing the line lombok.anyConstructor.addConstructorProperties = true. (If you are using modules, make sure java.desktop is on your module path.)

Solution 3: Use Jackson's builder support in combination with lombok's @Builder, as described here, or in @Randakar answer to this question.

Solution 4: When compiling with javac (of Java 8 and above), append -parameters to the command. This will store the parameter names of constructors and methods in the generated class files, so they can be retrieved via reflection.

Answer 2

You want to deserialize a class which has final field. so u need to declare a constructor which contains final field to deserialize.

@Data
@JsonInclude(JsonInclude.Include.NON_NULL)
@JsonIgnoreProperties(ignoreUnknown = true)
public class ErrorDetail {

private final String heading;
private final String detail;
private String type;

@JsonCreator
public ErrorDetail(@JsonProperty("heading") String heading, @JsonProperty("detail") String detail) {
    this.heading = heading;
    this.detail = detail;
}
}

and when deserialize with mapper need to MapperFeature.ALLOW_FINAL_FIELDS_AS_MUTATORS set this property false.

private static <T> T asObject(final String str, Class<T> clazz) {
    try {
        return new ObjectMapper().configure(MapperFeature.ALLOW_FINAL_FIELDS_AS_MUTATORS,false).readValue(str, clazz);
    } catch (Exception e) {
        throw new RuntimeException(e);
    }
}

Answer 3

Edit: This answer is now a bit outdated: There is a new @Jacksonized annotation, from https://projectlombok.org/features/experimental/Jacksonized, which takes care of much of the boilerplate in this answer.

---

The best way to make jackson and lombok play well together is to always make your DTO's immutable, and tell jackson to use the builder to deserialize into your objects.

Immutable objects are good idea for the simple reason that when fields cannot be modified in situ compilers can do much more aggressive optimisations.

In order to do this you need two annotations: JsonDeserialize, and JsonPojoBuilder.

Example:

@Builder
@Value // instead of @Data
@RequiredArgsConstructor
@NonNull // Best practice, see below.
@JsonDeserialize(builder = ErrorDetail.ErrorDetailBuilder.class)
@JsonInclude(JsonInclude.Include.NON_NULL)
@JsonIgnoreProperties(ignoreUnknown = true)
public class ErrorDetail {

   private final String heading;

   // Set defaults if fields can be missing, like this:
   @Builder.Default
   private final String detail = "default detail";

   // Example of how to do optional fields, you will need to configure
   // your object mapper to support that and include the JDK 8 module in your dependencies..
   @Builder.Default
   private Optional<String> type = Optional.empty()

   @JsonPOJOBuilder(withPrefix = "")
   public static final class ErrorDetailBuilder {
   }
}

Answer 4

Using @Data annotation is bad approach, in my opinion. Please change @Data to @Getting , @Setter, @EqualsAndHashcode and so on ..

and write here please, if it will help.

update

I suggest, that @Data create @RequiredArgsConstructor, and it is constructor with final fields, and without private String type;

Answer 5

Solution 4

• Write the NoArgsConstructor yourself. This at least worked for me with lombok 1.18.8 and Jackson 2.9.9

    @Builder
    @Getter
    @AllArgsConstructor
    public class EventDTO {

        private String id;
        private Integer isCancelled;

        private String recurringEventId;

        private String summary;
        private String description;
        private String location;
        private String startDateTime;
        private String endDateTime;

        /**
         * Make Jackson happy
         */
        public EventDTO() {
        }
    }