Is there an easy way to nest fields with jackson json annotations in java?

Question

I am looking for a way to do something like this without being forced to have to create a new separate object for the "content" value which would just hold a string inside the object.

@JsonNestedProperty("value.content")
String value = "my_value";

{
  "value": {
    "content": "my_value"
  }
}

Currently making new objects in order to nest fields

@JsonProperty("value")
MyContent value;

class MyContent {
  @JsonProperty("content")
  String content = "my_value";
}

Answer 1

You can use the ObjectWriter#withRootName method to wrap a distinct Content object with a string as a new rootname in the serialization process like the example below:

public class Content {

    @JsonProperty("content")
    String content = "my_value";
}

Content content = new Content();
//wrapping the Content obj with new rootname "value"
//it prints {"value":{"content":"my_value"}}
System.out.println(mapper.writer()
                         .withRootName("value")
                         .writeValueAsString(content));

If you want to wrap all Content objects with the same rootname you can annotate the Content class with the JsonRootName annotation and use the ObjectWriter#with method with the SerializationFeature#WRAP_ROOT_VALUE serialization feature like the example below:

@JsonRootName(value = "value")
public class Content {

    @JsonProperty("content")
    String content = "my_value";
}

Content content = new Content();
//it prints {"value":{"content":"my_value"}}
System.out.println(mapper.writer()
                         .with(SerializationFeature.WRAP_ROOT_VALUE)
                         .writeValueAsString(content));