Deserialize JSON array in a deserialized JSON array using Jackson

Question

I have a JSON structured like:

{
  "id" : "123",
  "name" : [ {
    "id" : "234",
    "stuff" : [ {
      "id" : "345",
      "name" : "Bob"
    }, {
      "id" : "456",
      "name" : "Sally"
    } ]
  } ]
}

I want to map to the following data structure:

Class01

@Getter
public class Class01{
    private String id;
    @JsonDeserialize(using = Class01HashMapDeserialize.class)
    private ArrayList<Class02> name;
}

Class02

@Getter
public class Class02{
    private String id;
    private ArrayList<Class03> stuff;
}

Class03

@Getter
public class Class03{
    private String id;
    private String name;
}

In my main Method im using an ObjectMapper with objectMapper.readValue(jsonString,new TypeReference<ArrayList<Class02>>(){}) to map this JSON to my Class01. This Class successfully deserealizes the Class02-array into the name array.

When it comes to the second array I don't know how to further deserialize as I am not able to access the json text from the class02 stuff entry.

@Override
public ArrayList<Class02> deserialize(JsonParser parser, DeserializationContext ctxt) throws IOException {
    ArrayList<Class02> ret = new ArrayList<Class02>();

    ObjectCodec codec = parser.getCodec();
    TreeNode classes02 = codec.readTree(parser);

    if (classes02.isArray()) {
        for (JsonNode class02 : (ArrayNode) classes02) {
            if(classe02.get("stuff").isArray()){
                 ObjectMapper objectMapper = new ObjectMapper();
                 ArrayList<Class03> classes03 = objectMapper.readValue(class02.get("stuff").asText(), new TypeReference<ArrayList<Class03>>(){});
            }
            ret.add(new Class02(class02.get("id").asText(), classes03));
        }
    }
    return ret;
}

Answer 1

Why did you put a @JsonDeserialize annotation? Jackson shall be able to deserialize it just fine without any custom mapping:

@Getter
public class Class01{
    private String id;
    private ArrayList<Class02> name;
}

Also in a first pass, I would generate the getters/setters/constructor manually for the 3 classes. There may be issues with Lombok & Jackson that you may want to solve later once you made the first version of the code works ( Can't make Jackson and Lombok work together )

And your reader shall be more like:

ObjectMapper objectMapper = new ObjectMapper();
String text = ... //Your JSon
Class01 class01 = objectMapper.readValue(text, Class01.class)