Question

Using org.apache.log4j.jdbc.JDBCAppender, how can I get stracktraces logged with warn and error into the PatternLayout.

I’m logging like

logger.warn("warning description", e);
logger.error("error description", e);

I get the String descriptions into the table, but the Throwable’s stacktrace is now where. Is there another parameter that I can access via the PatternLayout. Currently I am using

"INSERT INTO app_logs (app, log_date, log_level, location, loc, message) VALUES ('my-apps-name', '%d{ISO8601}','%p', '%C.java', '%C{1}.java:%L', '%m')" 

into a table

TABLE `app_logs` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `app` varchar(255) DEFAULT NULL,
  `log_date` varchar(255) DEFAULT NULL,
  `log_level` varchar(255) DEFAULT NULL,
  `location` varchar(255) DEFAULT NULL,
  `loc` varchar(255) DEFAULT NULL,
  `message` text, 
  PRIMARY KEY (`id`)
)

Answer 1

I found the solution.

Replace the PatternLayout class with the EnhancedPatternLayout class.

org.apache.log4j.EnhancedPatternLayout

You’ll also need to include the apache-log4j-extra dependency

Or include it in your pom:

<dependency>
  <groupId>log4j</groupId>
  <artifactId>apache-log4j-extras</artifactId>
  <version>1.1</version>
</dependency>

You now have access to %throwable

%throwable{short} or %throwable{1} will output the first line of stack
trace. throwable{none} or throwable{0} will suppress the stack trace.
%throwable{n} will output n lines of stack trace if a positive integer
or omit the last -n lines if a negative integer.

I added to my table,

TABLE `app_logs` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `app` varchar(255) DEFAULT NULL,
  `log_date` varchar(255) DEFAULT NULL,
  `log_level` varchar(255) DEFAULT NULL,
  `location` varchar(255) DEFAULT NULL,
  `loc` varchar(255) DEFAULT NULL,
  `message` text,
  `throwable` text,
  `stacktrace` text,
  PRIMARY KEY (`id`)
)

And updated my pattern to populate these columns.

"INSERT INTO app_logs (app, log_date, log_level, location, loc, message, throwable, stacktrace) VALUES ('my-apps-name', '%d{ISO8601}','%p', '%C.java', '%C{1}.java:%L', '%m', '%throwable{short}', '%throwable{100}')"