Better support when mapping null values.

[Brown-Dan]

It would be nice if we were able to annotate fields with something like
@IfNull(value = "methodName" )
private String genericfield

the value of the field when serialised would be whatever value that the method returns.

[pjfanning]

This Stackoverflow question has some answers that may help.

https://stackoverflow.com/questions/18805455/setting-default-values-to-null-fields-when-mapping-with-jackson

[cowtowncoder]

While I can see why this might be desireable, there is one immediate thing that makes me think it's a rat hole, and not something I'd want to climb into -- deserialization of "default value", String, would require additional logic for all kinds of things.
This is why @JsonSetter(nulls = ...) is limited to a set of options (null, "empty", , ).

One alternative possibility, however, could be allowing "provider" style object to be specified. That would require 2 new properties for @JsonSetter (nullProvider, valueNullProvider) or something, but would then allow customized handling -- granted, not quite as convenient as String