Changing POJO structure on returning to API call-CodePudding

I have assigned values to my POJO class to return as response body to an API call. I want to change my POJO structure, like by making the POJO as value to an object on top of the POJO.

For example:

Home POJO:

{
    int number;
    String address;
}

Values are assigned to the POJO and I can send it as response body to my API call, but I want my response body to be:

{
  output: {
      number: 1,
      address: "chennai"
    }
}

I know that I can achieve this using JSON-Object or using a HashMap or a parent POJO (Note: I do not want to create a POJO Output just for this case).

Is there any other way to serialize the POJO like this using Jackson or any other methods for Java with Spring?

CodePudding user response：

You can apply @JsonRootName annotation on your class specifying "output" as its value.

@JsonRootName("output")
public class MyPojo {
    private int number;
    private String address;
    
    // all-args constructor, getters, etc.
}

But this annotation alone would not have any impact on serialization. In order to make to instruct Jackson to use it, we need to enable the serialization feature WRAP_ROOT_VALUE:

Feature that can be enabled to make root value (usually JSON Object but can be any type) wrapped within a single property JSON object, where key as the "root name", ...

Usage example:

ObjectMapper mapper = new ObjectMapper();
mapper.enable(SerializationFeature.WRAP_ROOT_VALUE);
        
System.out.println(
    mapper
        .writerWithDefaultPrettyPrinter()
        .writeValueAsString(new MyPojo(1000, "foo"))
);

Output:

{
  "output" : {
    "number" : 1000,
    "address" : "foo"
  }
}