如何从 Jackson ObjectMapper 中排除空对象？

Question

Basically I do not want any empty JSON arrays or objects to show up in my generated JSON files. I have already configured my ObjectMapper accordingly using the following method:

objectMapper.setSerializationInclusion(Include.NON_EMPTY);

This works fine for arrays, collections and Strings. However if i have an empty object (= all properties are null or empty) it will still show up in the generated JSON like this:

"MyObject":{}

Here is a possible example of what I mean with an empty object:

class MyClass
{
    String property1 = "";
    Object property2 = null;
}

In this case I want the object to be excluded completely from the generated JSON file.

Is this possible? If yes, how to I have to configure my ObjectMapper in order to get the desired behavior?

Answer 1

To ignore the empty values such as you may have initialized the arrayList but there are no elements in that list. In that time using NOT_EMPTY annotation to ignore those empty value fields

@JsonInclude(Include.NON_EMPTY)
class Foo
{
  String bar;
}

Answer 2

It's been a few years since the question was asked, but I hit this page looking for a solution. So here it is.

You need to annotate your class with NON_DEFAULT:

@JsonInclude(NON_DEFAULT)
class MyClass
{
  String property1 = "";
  Object property2 = null;
}

Global config is not enough as explicitly stated in the documentation: http://fasterxml.github.io/jackson-annotations/javadoc/2.7/com/fasterxml/jackson/annotation/JsonInclude.Include.html#NON_DEFAULT

The new NON_DEFAULT is available since 2.7