Question

I have the following json:

{
  "id":"myid",
  "fields":{
    "body":"text body"
    }
}

which I want to deserialize into the following Java class:

class TestItem {
private String id;
private String body;

public String getId() {
    return id;
}

public void setId(String id) {
    this.id = id;
}

public String getBody() {
    return body;
}

public void setBody(String body) {
    this.body = body;
}

using the Jackson Json deserializer. This doesn’t work because the body field is nested inside a fields inner class.

I can’t change the json structure, so is there any way (perhaps using annotations) I can remap of the body field up from TestItem.fields.body to TestItem.body?

Edit:
I should have said this is part of a larger class hierarchy and the aim of the excercise is to reduce the depth of it. In other words, I know that I COULD declare an inner class and then access that, but that is not what I’m trying to achieve.

Answer 1

There are couple of feature requests that (if implemented) would allow limited one-level wrapping/unwrapping. But currently there is no declarative way to do this. And to some degree it is edge case, since this goes into data transformation as opposed to data binding (unfortunately I can’t think of good object transformation libs, so there may be bit of gap there).

What is usually done, then, is to do two-phase binding: first into intermediate types (often java.util.Map, or jackson JsonNode (Tree model)); modify those, and then convert from this type to actual result. For example something like this:

JsonNode root = mapper.readTree(jsonSource);
// modify it appropriately (add, remove, move nodes)
MyBean bean = mapper.convertValue(root, MyBean.class);