Java lombok universal field for list of objects

Question

I have json response from api with structure like this:

{
    "countPerPage": 20,
    "totalCount": 401,
    "currentPage": 1,
    "totalPage": 21,
    "data": [
        {
            "id": 1,
            "catId": 12,
            "dogId": 12,
            "creationDate": "2022-01-03 12:29:38",
            "comment": "Some comment"
        },
        {
            "id": 2,
            "catId": 13,
            "dogId": 16,
            "creationDate": "2022-01-08 11:14:25",
            "comment": "Some comment"
        },
        ...
    ]
}

and like this

{
    "countPerPage": 20,
    "totalCount": 226,
    "currentPage": 3,
    "totalPage": 12,
    "data": [
        {
            "id": 1,
            "parentId": 12,
            "firstName": "John",
            "lastName": "Doe",
            "creationDate": "2022-01-03 12:29:38",
            "age": 25
        },
        {
            "id": 1,
            "parentId": 12,
            "firstName": "Michael",
            "lastName": "Finder",
            "creationDate": "2022-01-08 11:14:25",
            "age": 24
        },
        ...
    ]
}

And other with same structure.

If I create response java classes for person like this

@Data
@JsonIgnoreProperties(ignoreUnknown = true)
public class PersonResponse{
    @JsonProperty("id")
    private int id;

    @JsonProperty("parentId")
    private int parentId;

    @JsonProperty("firstName")
    private String firstName;

    @JsonProperty("lastName")
    private String lastName;

    @JsonProperty("creationDate")
    private String creationDate;

    @JsonProperty("age")
    private int age;
}

@Data
@JsonIgnoreProperties(ignoreUnknown = true)
public class PersonWithCount {
    @JsonProperty("countPerPage")
    private int countPerPage;

    @JsonProperty("totalCount")
    private int totalCount;

    @JsonProperty("currentPage")
    private int currentPage;

    @JsonProperty("totalPage")
    private int totalPage;

    @JsonProperty("data")
    private List<PersonResponse> data;
}

And for animal like this

@Data
@JsonIgnoreProperties(ignoreUnknown = true)
public class AnimalResponse{
    @JsonProperty("id")
    private int id;

    @JsonProperty("catId")
    private int catId;

    @JsonProperty("dogId")
    private int dogId;

    @JsonProperty("creationDate")
    private String creationDate;

    @JsonProperty("comment")
    private String comment;
}

@Data
@JsonIgnoreProperties(ignoreUnknown = true)
public class AnimalWithCount {
    @JsonProperty("countPerPage")
    private int countPerPage;

    @JsonProperty("totalCount")
    private int totalCount;

    @JsonProperty("currentPage")
    private int currentPage;

   @JsonProperty("totalPage")
    private int totalPage;

    @JsonProperty("data")
    private List<AnimalResponse> data;
}

All works korrect. But how can I use something universal like generics, for don't copy and paste each time class with same data, where changed only last field?

I expected something like this, but it is not working

@Data
@JsonIgnoreProperties(ignoreUnknown = true)
public class DataWithCount<T> {
    @JsonProperty("countPerPage")
    private int countPerPage;

    @JsonProperty("totalCount")
    private int totalCount;

    @JsonProperty("currentPage")
    private int currentPage;

    @JsonProperty("totalPage")
    private int totalPage;

    @JsonProperty("data")
    private List<T> data;
}

Fill variable:

personListWithCount = ObjectMapperCreator.objectMapperCreator().readValue(personResponse.getBody().asPrettyString(), PersonListWithCount.class);

Maybe I do something wrong?

I can't set generic type, because PersonListWithCount.class can't be like PersonListWithCount.class as param — Andrej, Oct 04 '22 at 07:41
@viking Create and retun ObjectMapper with params ACCEPT_EMPTY_ARRAY_AS_NULL_OBJECT, ACCEPT_SINGLE_VALUE_AS_ARRAY, FAIL_ON_UNKNOWN_PROPERTIES — Andrej, Oct 04 '22 at 08:05

Andrej · Answer 1 · 2022-10-04T08:38:48.233

0

Helped answer from other question (Jackson - Deserialize using generic class):

mapper.readValue(jsonString, new TypeReference<DataWithCount<AnimalResponse>>() {});

and second way works too

JavaType type = mapper.getTypeFactory().constructParametricType(DataWithCount.class, AnimalResponse.class);
DataWithCount<AnimalResponse> data = mapper.readValue(json, type);

Thank you @Nick

edited Oct 04 '22 at 08:38

answered Oct 04 '22 at 08:08

Andrej

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Java lombok universal field for list of objects

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