How to accept an arbitary JSON object?

Question

I've got a Jax-rs endpoint that accepts JSON analogous to:

{
"a": 1,
"b": "some value",
"c": { <-some-arbitary-json-object-> }
}

In my DTO, a and b are no issue. What do I do with c? I need only to serialize it again (or, indeed, just read it as a String), I don't need to process it in any way. I do need to do things with a and b, so I can't just treat the entire body as a String.

What data type do I need to give it so that jax-rs/jersey can deserialize it?

I can't help but feel I'm missing something obvious.

Answer 1

I worked out one way, but I feel I'm probably re-inventing the wheel. I defined a custom deserializer to read in the arbitary JSON then serialise it again:

public class JsonAsStringDeserializer extends JsonDeserializer<String> {
    private final ObjectMapper mapper = new ObjectMapper();
  @Override
  public String deserialize(JsonParser p, DeserializationContext ctx)
          throws IOException {
     TreeNode node = mapper.readTree(p);
     return mapper.writeValueAsString(node);
      
  }
}

And in the model POJO:

@JsonDeserialize(using = JsonAsStringDeserializer.class) 
private String c = null;