How to unwrap nested json object as an entity

Question

I am calling another api and get the below json response

{
    "metadata": {},
    "data": {
        "productId": 102001,
        "productName": "P101",

        "brandDetail": {
            "brandId": 3840,
            "brandName": "ABC",
            "brandCode": "X01"
        }
    }
}

How do I unwrap the brand details and read it as a class entity like below?

    HttpGet httpGet = buildHttpGet("/externalApiURL");
    HttpResponse response = getHttpClient().execute(httpGet);
    HttpEntity entity = response.getEntity();

    if (entity != null && response.getStatusLine().getStatusCode() == HttpStatus.OK.value()) {
        ObjectMapper objectMapper = new ObjectMapper();
        BrandDetail brandDetail = objectMapper.readValue(entity.getContent(), BrandDetail.class);
    }

Thanks in advance

Answer 1

Use the convertValue(), here is an test.

@Data
public class BrandDetail {
    private int brandId;
    private String brandName;
    private String brandCode;
}

@Test
public void demo() throws Exception {
    ObjectMapper mapper = new ObjectMapper();
    var data = """
            {
                "metadata": {},
                "data": {
                    "productId": 102001,
                    "productName": "P101",
                    "brandDetail": {
                        "brandId": 3840,
                        "brandName": "ABC",
                        "brandCode": "X01"
                    }
                }
            }
            """;
    JsonNode node = mapper.readTree(data);
    JsonNode brandNode = node.get("data").get("brandDetail");
    BrandDetail brandDetail = mapper.convertValue(brandNode, BrandDetail.class);
    // BrandDetail(brandId=3840, brandName=ABC, brandCode=X01)
    System.out.println(brandDetail);
}