How can I set a pattern in a DBAppender? - logback

Question

I using logback and put a pettern into a dbappender, but it doesn´t work.
<appender name="DB" class="ch.qos.logback.classic.db.DBAppender">
<connectionSource
class="ch.qos.logback.core.db.DriverManagerConnectionSource">
<driverClass>net.sourceforge.jtds.jdbc.Driver</driverClass>
<url>jdbc:jtds:sqlserver://xxx.xxx.xxx.xx:1433/granica</url>
<user>java</user>
<password>java</password>
</connectionSource>
<encoder>
<pattern>%d{HH:mm:ss.SSS} - %msg%n</pattern>
</encoder>
</appender>
someone know how to fix that?
thanks in advance!

Answer 1

You can't put a pattern in a DBAppender:
"The DBAppender inserts logging events into three database tables in a format independent of the Java programming language.
*These three tables are logging_event, logging_event_property and logging_event_exception. They must exist before DBAppender can be used. Logback ships with SQL scripts that will create the tables."*
Alternative solution: If you realy need this pattern, then you should create an extra dataBbase table/view/sql that generaties that output for you, based on the existing tables. This can be done with a simple SQL, View or Triggers. Use standard SQL to create the output you need.
Good luck!

Answer 2

I managed to customize the formatted message easily enough by defining a couple of custom classes, one extending the DBAppender and the other implementing the ILoggingEvent interface:
package com.mypackage;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.util.Map;
import org.slf4j.Marker;
import ch.qos.logback.classic.Level;
import ch.qos.logback.classic.db.DBAppender;
import ch.qos.logback.classic.spi.ILoggingEvent;
import ch.qos.logback.classic.spi.IThrowableProxy;
import ch.qos.logback.classic.spi.LoggerContextVO;
/**
*
* #author PJ_Finnegan
*
* To override the default DBAppender with a custom FORMATTED_MESSAGE
*
*/
public class MdcDbAppender extends DBAppender {
#Override
protected void subAppend(ILoggingEvent event, Connection connection, PreparedStatement insertStatement)
throws Throwable {
// use a special event with custom formatted message
MdcLoggingEvent customEvent = new MdcLoggingEvent(event);
super.subAppend(customEvent, connection, insertStatement);
}
}
/**
*
* #author PJ_Finnegan
*
* To override the getFormattedMessage() method prepending MDC info
*
*/
class MdcLoggingEvent implements ILoggingEvent {
private ILoggingEvent mOrigEvent;
public MdcLoggingEvent(ILoggingEvent origEvent) {
mOrigEvent = origEvent;
}
#Override
public String getThreadName() {
return mOrigEvent.getThreadName();
}
#Override
public Level getLevel() {
return mOrigEvent.getLevel();
}
#Override
public String getMessage() {
return mOrigEvent.getMessage();
}
#Override
public Object[] getArgumentArray() {
return mOrigEvent.getArgumentArray();
}
#Override
public String getFormattedMessage() {
// add my MDC info as a prefix
String mdcVals[] = new String[] { "NA", "NA", "NA" };
Map<String, String> mpm = mOrigEvent.getMDCPropertyMap();
if (mpm != null) {
int i = 0;
for (String key : new String[] { "jobName", "jobInstanceId", "jobExecutionId" }) {
if (mpm.containsKey(key)) {
mdcVals[i] = mpm.get(key);
}
i++;
}
}
return String.format("[%s-%s-%s] ", mdcVals[0], mdcVals[1], mdcVals[2]) + mOrigEvent.getFormattedMessage();
}
#Override
public String getLoggerName() {
return mOrigEvent.getLoggerName();
}
#Override
public LoggerContextVO getLoggerContextVO() {
return mOrigEvent.getLoggerContextVO();
}
#Override
public IThrowableProxy getThrowableProxy() {
return mOrigEvent.getThrowableProxy();
}
#Override
public StackTraceElement[] getCallerData() {
return mOrigEvent.getCallerData();
}
#Override
public boolean hasCallerData() {
return mOrigEvent.hasCallerData();
}
#Override
public Marker getMarker() {
return mOrigEvent.getMarker();
}
#Override
public Map<String, String> getMDCPropertyMap() {
return mOrigEvent.getMDCPropertyMap();
}
#Override
public Map<String, String> getMdc() {
return mOrigEvent.getMdc();
}
#Override
public long getTimeStamp() {
return mOrigEvent.getTimeStamp();
}
#Override
public void prepareForDeferredProcessing() {
mOrigEvent.prepareForDeferredProcessing();
}
}
This way the LOGGING_EVENT.FORMATTED_MESSAGE column values on the DB will have the string [jobName-jobInstanceId-jobExecutionId] (whose value I had previously put in MDC) prepended:
TIMESTMP
FORMATTED_MESSAGE
1635255763784
[test-2760-3980] HikariPool-1 - Shutdown completed.
Of course you want to use your custom class in your logback.xml file instead of the stock DBAppender:
<!-- DB appender -->
<!-- use our custom class to override the FORMATTED_MESSAGE default pattern -->
<!-- <appender name="ORADB" class="ch.qos.logback.classic.db.DBAppender"> -->
<appender name="ORADB" class="com.mypackage.MdcDbAppender">
<connectionSource
...
Nothing prevents from overriding the ILoggingEvent.getFormattedMessage() method with more elaborated manipulations.