Log4NET AdoNetAppender connection string reference

.net, c#, log4net, web-config

Solution

Edit: since this was posted, log4net now supports specifying the connection string name in the config. From https://issues.apache.org/jira/browse/LOG4NET-88 -

This adds a new "connectionStringName" attribute (and corresponding ConnectionStringName) property to the AdoNetAppender class. This is a reference to a connection string within the `<ConnectionStrings>` section of an App.config or Web.config file.

There's an example in this answer.

If you don't have the connection string defined in the `<ConnectionStrings>` section then you can set the connection string at runtime using this class:

You invoke `SetConnectionString` with the connection string just after you've configured log4net.

However, there are a couple of things I would note:

Log4net database appenders don't like being created without a connection string, and throw an (internal) error - and during unit testing, I've seen tests take more than 10 seconds when given a fake connection string.

public static class LogConfigurator
{
   public static void SetConnectionString(string connectionString)
   {
        Hierarchy logHierarchy = log4net.LogManager.GetRepository() as Hierarchy;

        if (logHierarchy == null)
        {
            throw new InvalidOperationException
               ("Can't set connection string as hierarchy is null.");
        }

        var appender = logHierarchy.GetAppenders()
                                   .OfType<AdoNetAppender>()
                                   .SingleOrDefault();

        if (appender == null)
        {
            throw new InvalidOperationException
              ("Can't locate a database appender");
        }

        appender.ConnectionString = connectionString;
        appender.ActivateOptions();
   }
}

Problem

Original source

Related problems

• Can you pull the connectionString for a log4net AdoNetAppender from elsewhere in a web.config file?