Logback allows adding key-value pairs to events. But the only way I've found to use them is the %kvp option in the formatter, that just dumps all of the key="value" pairs.
Isn't there any way to insert the values (I don't care about logging the key), separated at specific places in the format ?
It seems to be doable with %X for MDC elements, but not for simple key pairs.
Alternatively I guess I could use MDC for this, but then I would be basically changing my value for each event. It did not seem to me it was meant for this kind of use.
As luck would have it I also ran into this problem today!
It's not a fantastic solution but one way would be to use a regex like so, assuming you have a property in your key value pair list named myProperty, and assuming that, like most people, you are using the pattern encoder:
%replace(%kvp){'.*myProperty="([^"]+)".*', '$1'}
breaking down the regex:
.* - match any character 0 or more timesmyProperty= - exact string match"([^"])" - one or more of any non-double quote character which are between the next two double quotes, place into capture group 1.* - any character 0 or more timesthen $1 in the second argument replaces the whole key-value string with the contents of capture group 1
Now, we just need to remove this key-value from the %kvp output we put in our log message, it is similar. Assuming you have some additionalData field in your log message:
additionalData={%replace(%kvp{DOUBLE}){'[\s]{0,1}myProperty="[^"]"', ''}}
Please note this regex could leave extra whitespace in the resulting string if it is the first element. To remedy this you can wrap this regex in a second one to remove any leading whitespace:
additionalData={%replace(%replace(%kvp{DOUBLE}){'[\s]{0,1}myProperty="[^"]"', ''}}){'^\s+', ''}
It's terse, but you can play around with the regex at regex101 or some similar interactive tool.
If you'd like to avoid all this regex ugliness, you can also try registering a custom conversion specifier to do the heavy lifting for you, I have not tried this route though.