[logback-user] Split long data on multiple rows

Ceki Gulcu ceki at qos.ch
Tue Sep 22 13:59:56 CEST 2009

Since you system is based on logback-core and not logback-classic, you could 
create a turbo filter which instead of returning ACCEPT, DENY, NEUTRAL could 
return an array of MyEvent instances which would correspond closely to what you 
have in mind.

Anders Hammar wrote:
> Thanks Ceki! I knew I could count on you replying quickly.
> The framework here is the auditing framework I constructed some 1,5 
> years ago for a customer. They've now realized this requirement.
> I was kind of hoping that I could add some step before the layout gets 
> the event. In that step, I could check the event, and if necessary split 
> it into x events. And then the layout would get these n events instead 
> and do the normal logging on each of them.
> I had a look at the filters, but they only handle allow/block kind of 
> things. This would be some other kind of "filter". Maybe there's no 
> advantage going down this path compared to your suggestion...
> /Anders
> On Tue, Sep 22, 2009 at 11:38, Ceki Gulcu <ceki at qos.ch 
> <mailto:ceki at qos.ch>> wrote:
>     Hello Anders,
>     Logback-core? Nice.
>     If only the field 'foo' needs to be split, then just override the
>     converter for the field foo to do the splitting, and you are done.
>     However, you requirements differ as you also require the repetition
>     of other fields.
>     The approach which seems the most logical to me, would be to derive
>     a sub-class from PatternLayoutBase overriding the
>     writeLoopOnConverters method so that when the foo field needs
>     splitting, you would loop over the converter chain as many times as
>     necessary.
>     Here is a possible implementation:
>     class MyPatternLayout extends PatternLayoutBase<MyEvent> {
>      ...
>      protected String writeLoopOnConverters(MyEvent event) {
>        Foo foo = event.getFoo();
>        StringBuilder sb = new StringBuilder();    
>        String[] fooParts = split(foo);
>        for(String s: fooParts) {
>          // construct a new event from 'event' so that foo has only one part
>          MyEvent splitEvent = new MyEvent(event, s);
>          String line = super.writeLoopOnConverters(splitEvent);
>          sb.append(line);
>          sb.append(CoreConstants.LINE_SEPARATOR);
>        }
>        return sb.toString();
>      }
>     }
>     HTH,
>     Anders Hammar wrote:
>         Hi,
>         I have a framework that utilizes logback-core for logging. Due
>         to limitations in the software reading the log files, a new
>         requirement is that long data should be split on multiple rows.
>         I'm trying to figure out if there a simple way of doing this?
>         More info: What I have is an extension of the PatternLayoutBase
>         which adds the converters for my event class. I'm using the
>         standard RollingFileAppender. So, let's say I have a
>         FooConverter, which gets the foo info from the event. But, when
>         logging to the file, the foo info part must never be longer than
>         x chars. If it is, it should be split on multiple rows. Other
>         data (generated by other converters) should then be repeated.
>         Any suggestions on how to do this in a clean logback way is
>         appreciated! What I'm currently thinking is to loop on the
>         converters (calling PatternLayoutBase.writeLoopOnConverters
>         multiple times), but I need to know when that's required...
>         Anyone done something similar?
>         /Anders
>     -- 
>     Ceki Gülcü
>     Logback: The reliable, generic, fast and flexible logging framework
>     for Java.
>     http://logback.qos.ch
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Ceki Gülcü
Logback: The reliable, generic, fast and flexible logging framework for Java.

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