CODEWITHSUNDEEP
javajacksondeserializationjackson-databind
tschik
tschik

Reputation: 13

How to deserialize a List of String to a single arg value class?

Basically I always want to unwrap my Id class to the parent object but in case of a List<> I can not use the JsonUnwrapped Annotation from the jackson library.

@lombok.Value
public class Response {
  List<MyId> ids;
  // ... other fields
}

@lombok.Value
public class MyId {
  String id;
}


{
  "ids": ["id1", "id2"]
  "otherField": {}
}

Working solution with jackson-databind 2.11

@lombok.Value
public class MyId {
  @JsonValue
  String id;

  public MyId(final String id) {
    this.id = id;
  }
}

Upvotes: 0

Views: 199

Answers (1)

Smile
Smile

Reputation: 4088

You can use @JsonValue. From docs:

Marker annotation that indicates that the value of annotated accessor (either field or "getter" method [a method with non-void return type, no args]) is to be used as the single value to serialize for the instance, instead of the usual method of collecting properties of value. Usually value will be of a simple scalar type (String or Number), but it can be any serializable type (Collection, Map or Bean).

Usage:

@Value
public class MyId {
    @JsonValue
    String id;
}

Complete code:

public class JacksonExample {

    public static void main(String[] args) throws JsonProcessingException {
        ObjectMapper objectMapper = new ObjectMapper();
        List<MyId> myIds = new ArrayList<>();
        MyId id1 = new MyId("one");
        MyId id2 = new MyId("two");
        myIds.add(id1);
        myIds.add(id2);
        Response response = new Response(myIds, "some other field value");
        System.out.println(objectMapper.writeValueAsString(response));
    }
}

@Value
class Response {
    List<MyId> ids;
    String otherField;
}

@Value
class MyId {
    @JsonValue
    String id;
}

Output:

{
  "ids": [
    "one",
    "two"
  ],
  "otherField": "some other field value"
}

Upvotes: 1

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