Jason Newell created LOG4NET-655:
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Summary: CONFIGURATION - Load extension assemblies by
configuration reference
Key: LOG4NET-655
URL: https://issues.apache.org/jira/browse/LOG4NET-655
Project: Log4net
Issue Type: New Feature
Components: Layouts
Reporter: Jason Newell
h1. The problem
Currently to extend the layout the extension code needs to be in the main dll
or exe as it has to be loaded at startup for log4net to be able to find the
layout extension. In order to create the ability to have these extensions in an
assembly which can be shared with other projects there needs to be a way to
tell log4net via the configuration which assembly to load.
h2. An example of a layout extension
h3. C# Code
public class FileNamePatternConverter : PatternLayoutConverter
{
/// <inheritdoc />
protected override void Convert(TextWriter clsTextWriter, LoggingEvent
clsLoggingEvent)
{
clsTextWriter.Write(Path.GetFileName(clsLoggingEvent.LocationInformation.FileName));
}
}
h3. Configuration
<layout type="log4net.Layout.PatternLayout">
<converter>
<name value="filename" />
<type value="X.Logging.FileNamePatternConverter" />
</converter>
<conversionPattern value="[%5level] %date\{dd MMM yyyy HH:mm:ss}
%filename:%line %logger - %message%newline" />
</layout>
h3. Error message
log4net:ERROR Could not create Appender [RollingFile] of type
[log4net.Appender.RollingFileAppender]. Reported error follows.
System.TypeLoadException: Could not load type
[X.DotNet.Logging.FileNamePatternConverter]. Tried assembly [log4net,
Version=2.0.11.0, Culture=neutral, PublicKeyToken=669e0ddf0bb1aa2a] and all
loaded assemblies
at log4net.Util.SystemInfo.GetTypeFromString(Assembly relativeAssembly, String
typeName, Boolean throwOnError, Boolean ignoreCase)
at
log4net.Repository.Hierarchy.XmlHierarchyConfigurator.SetParameter(XmlElement
element, Object target)
at
log4net.Repository.Hierarchy.XmlHierarchyConfigurator.CreateObjectFromXml(XmlElement
element, Type defaultTargetType, Type typeConstraint)
at
log4net.Repository.Hierarchy.XmlHierarchyConfigurator.SetParameter(XmlElement
element, Object target)
at
log4net.Repository.Hierarchy.XmlHierarchyConfigurator.CreateObjectFromXml(XmlElement
element, Type defaultTargetType, Type typeConstraint)
at
log4net.Repository.Hierarchy.XmlHierarchyConfigurator.SetParameter(XmlElement
element, Object target)
at
log4net.Repository.Hierarchy.XmlHierarchyConfigurator.ParseAppender(XmlElement
appenderElement)
log4net:ERROR Appender named [RollingFile] not found.
h1. Proposed Solution
{color:#172b4d}Add a line to the converter configuration to force the loading
of the assembly.{color}
<layout type="log4net.Layout.PatternLayout">
<converter>
<name value="filename" />
<type value="X.Logging.FileNamePatternConverter" />
*{color:#4c9aff}<assembly value="XLoggingExtensions" />{color}*
</converter>
<conversionPattern value="[%5level] %date\{dd MMM yyyy HH:mm:ss}
%filename:%line %logger - %message%newline" />
</layout>
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