implementing Jackson Deserialization of Nested JSON with Optional Fields in Java 17
I'm testing a new approach and I've searched everywhere and can't find a clear answer... I'm working with an scenario when attempting to deserialize a nested JSON structure using Jackson in my Java 17 application. The JSON occasionally omits certain fields, which are represented as `Optional` in my data classes. When the deserialization encounters these missing fields, it throws an `UnrecognizedPropertyException`, which is not what I expected. I thought using `@JsonInclude(JsonInclude.Include.NON_ABSENT)` would prevent this behavior, but it seems insufficient. Here’s a simplified version of my data class: ```java import com.fasterxml.jackson.annotation.JsonInclude; import com.fasterxml.jackson.annotation.JsonProperty; import java.util.Optional; @JsonInclude(JsonInclude.Include.NON_ABSENT) public class User { private String name; private Optional<Address> address; // Getters and setters } @JsonInclude(JsonInclude.Include.NON_ABSENT) public class Address { private String city; private String zip; // Getters and setters } ``` And here’s the JSON I’m trying to deserialize: ```json { "name": "John Doe" // "address" field is omitted } ``` I am using the following code to perform the deserialization: ```java import com.fasterxml.jackson.databind.ObjectMapper; ObjectMapper objectMapper = new ObjectMapper(); User user = objectMapper.readValue(jsonString, User.class); ``` However, I keep working with the following behavior: ``` com.fasterxml.jackson.databind.exc.UnrecognizedPropertyException: Unrecognized field "address" ``` I’ve attempted to add `@JsonProperty` annotations with `required = false`, but that hasn't resolved the scenario either. Additionally, I’ve checked the Jackson version and confirmed I’m using `2.13.0`. How can I configure Jackson to gracefully handle this scenario without throwing an exception when working with optional fields that are absent in the JSON? Any insights or best practices would be appreciated. My development environment is Windows. My development environment is Ubuntu 20.04. Is there a better approach?