Enable Object Mapper writeValueAsString method to include null values

Question

I have a JSON object which may contain a few null values. I use ObjectMapper from com.fasterxml.jackson.databind to convert my JSON object as String.

private ObjectMapper mapper = new ObjectMapper();
String json = mapper.writeValueAsString(object);

If my object contains any field that contains a value as null, then that field is not included in the String that comes from writeValueAsString(). I want my ObjectMapper to give me all fields in the String even if their value is null.

Example:

object = {"name": "John", "id": 10}
json   = {"name": "John", "id": 10}

object = {"name": "John", "id": null}
json   = {"name": "John"}

Answer 1

Include.ALWAYS worked for me. objectMapper.setSerializationInclusion(com.fasterxml.jackson.annotation.JsonInclude.Include.ALWAYS);

Other possible values for Include are:

• Include.NON_DEFAULT
• Include.NON_EMPTY
• Include.NON_NULL