src/log4php/appenders/LoggerAppenderMongoDB.php
protected function formatThrowable(Exception $ex) {
		$array = array(				
			'message' => $ex->getMessage(),
			'code' => $ex->getCode(),
			'stackTrace' => $ex->getTraceAsString(),
		);
        
		if (method_exists($ex, 'getPrevious') && $ex->getPrevious() !== null) {
			$array['innerException'] = $this->formatThrowable($ex->getPrevious());
		}
		
		return $array;
	}
protected function formatThrowable(Exception $ex) {
		$array = array(				
			'message' => $ex->getMessage(),
			'code' => $ex->getCode(),
			'stackTrace' => $ex->getTraceAsString(),
		);
        
		if (method_exists($ex, 'getPrevious') && $ex->getPrevious() !== null) {
			$array['innerException'] = $this->formatThrowable($ex->getPrevious());
		}
		
		return $array;
	}
Converts an Exception into an array which can be logged to mongodb.

Supports innner exceptions (PHP >= 5.3)

@param Exception $ex
@return array