<pattern>: do not include property when value is empty/null

Suppose the following pattern:

<pattern>
{
   "trace": "%mdc{traceId}"
}
</pattern>

Is there a way to omit the trace property when there is no such traceId MDC key? Something like what #nullNA{...} does for Access events…

[kharnt0x]

we would definitely welcome this feature

[philsttr]

@wsargent If my understanding is correct, this request is more about excluding a specific field within a pattern based on the the field’s evaluated value, rather than excluding the whole pattern based on a value.

i.e. if the pattern is something like this:

{
    "trace": "%mdc{traceId}",
    "foo": "bar"
}

Then only the trace field would be omitted if the field value evaluated to null. The foo field would still be included regardless.

You could work around this by separating out every possible nullable thing into a different pattern, but that would be cumbersome when working with a large pattern.