Jackson - 自定义反序列化器不会读取 JSON 中的所有字段

Question

I am receiving from the API this JSON:

    "link": [],
    "firstRecord": 1,
    "item": [
        {
            "Customer": {
                "id": "1058207",
                "firstName": "foo",
                "lastName": "foo2",
                "nestedObj1": {
                    "id": "40008"
                },
                "nestedObj2": {
                    "link": [],
                    "linkfoo": "lala",
                    "item": [
                             {
                              "id": "266614",
                              "label": "NESTED_OBJ_2"
                            }
                           ]
                  }
              ]
           }

My Deserializer function

    @Override
    public CustomerView deserialize(JsonParser p, DeserializationContext ctxt)
            throws IOException, JsonProcessingException {

        //tried this too
        TreeNode treeNode = p.getCodec().readTree(p);

        // also this
        JsonNode node = p.getCodec().readTree(p);

        JsonNode simpleNode = new ObjectMapper().readTree(p);

        // use for each field that is not String
        ObjectMapper mapper = new ObjectMapper();

        Customer customer = new Customer();

        customer.setFirstName(simpleNode.get("Customer").get("firstName").textValue()); 

        NestedObj2[] arrayObj2 = mapper.readValue(
                        simpleNode.get("Customer").get("nestedObj2").get("item").toString(), 
                        NestedObj2[].class);

        customer.setArrayObj2(arrayObj2);
}

Class NestedObj2 has all the fields as in the JSON, "item" array is separate object as a field.

The problem is, that neither JsonNode nor TreeNode, doesn't see field "nestedObj2", but the rest of the fields are inside them while deserializing -> checked while debugging.

Do I miss something in configuration, or should I use other object to deserialize?

Thanks!

EDIT

In the end I've used DTO as @Mehrdad HosseinNejad advised. As I'm receiving this JSON by RestTemplate.exchange() , I had to configure RestTemplate with MappingJacksonHttpMessageConverter like here https://stackoverflow.com/a/9381832/12677470

Answer 1

Use of DTO classes may be a better idea, there is no need to create custom deserializer

I coded an example nested DTO as follows

Create DTO class for Customer

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

private Long id;
private String firstName;
private String lastName;
private NestedObj1 nestedObj1;
private NestedObj2 nestedObj2;

//getter and setter

}

Create DTO class for NestedObj1

@JsonInclude(JsonInclude.Include.NON_NULL)
@JsonIgnoreProperties(ignoreUnknown = true)
public class NestedObj1 {

private Long id;

//getter and setter

}

Create DTO class for NestedObj2

@JsonInclude(JsonInclude.Include.NON_NULL)
@JsonIgnoreProperties(ignoreUnknown = true)
public class NestedObj2 {

private List<String> link;
private String linkFoo;
private List<Item> item;

//getter and setter     

}

Create DTO class for Item

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

private Long id;
private String label;

//getter and setter

}

After creating these DTO's you can simply using ObjectMapper class convert your JSON to Java Object

Customer customer= new ObjectMapper().readValue(jsonFile, Customer.class);

For more options like ignore some property,... you can use the below link:

Jackson Annotation Examples

More information in Deserialization:

Getting Started with Deserialization in Jackson