Question

I have an object that is curently being serialized to:

{
  "label" : "label",
  "proxyIds" : [ ],
  "childIds" : [ 161, 204, 206, 303, 311 ],
  "actionIds" : [ 157, 202 ],
}

That proxyIds is an empty (not null) collection in the java object.

How do I configure Jackson to not include that object in the json at all?

I want behaviour similar to “unwrapped” collections in xml/soap where if the collection is empty it is not included. I do not need to distinguish between null and empty collection and want to reduce the size of the json payload.

Answer 1

This may be a long shot but how about using Inclusions and defining NON_DEFAULT as the inclusion property. The docs say:

“Value that indicates that only properties that have values that differ from default settings (meaning values they have when Bean is constructed with its no-arguments constructor) are to be included.”

So if the default value is an empty array it should skip it.

Something like:

ObjectMapper mapper = new ObjectMapper();
mapper.getSerializationConfig().setSerializationInclusion(Inclusion.NON_DEFAULT);


public class Test {
     String[] array = { };
     ....
}

http://jackson.codehaus.org/1.1.2/javadoc/org/codehaus/jackson/map/annotate/JsonSerialize.Inclusion.html