Logging Linq to SQL

There are times when you need a quick way to debug Linq to SQL. Inspired by this answer to a StackOverflow question I easily combined log4net and Linq to SQL. This way I avoided the console, which is not an option in the case of a web application.

It is possible to set the Log property of your DataContext. Log is a TextWriter, so I created a simple TextWriter implementation. Not sure which methods L2S uses, I overrided Write and WriteLine where they take string and object parameters. Each implementation simply logs to log4net but, naturally, it could use any logging library.

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public partial class YourDataContext
{
   partial void OnCreated()
   {
      #if DEBUG
         this.Log = new LogWriter();
      #endif
   }

    class LogWriter : TextWriter
    {
        public override Encoding Encoding
        {
            get { return Encoding.UTF8; }
        }

        public override void Write(string format, object arg0)
        {
            // logging goes here
        }

        public override void Write(object value)
        {
            // logging goes here
        }

        public override void Write(string format, object arg0, object arg1)
        {
            // logging goes here
        }

        public override void Write(string format, object arg0, object arg1, object arg2)
        {
            // logging goes here
        }

        public override void Write(string format, params object[] arg)
        {
            // logging goes here
        }

        public override void Write(string value)
        {
            // logging goes here
        }

        public override void WriteLine(string format, object arg0)
        {
            // logging goes here
        }

        public override void WriteLine(object value)
        {
           // logging goes here
        }

        public override void WriteLine(string format, object arg0, object arg1)
        {
            // logging goes here
        }

        public override void WriteLine(string format, object arg0, object arg1, object arg2)
        {
            // logging goes here
        }

        public override void WriteLine(string format, params object[] arg)
        {
            // logging goes here
        }

        public override void WriteLine(string value)
        {
            // logging goes here
        }
    }
}

In my case I used log4net and here is my configuration, which logs to a file:

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<log4net>
   <appender name="LinqFile"
      type="log4net.Appender.FileAppender">
      <file value="Logs/Linq2Sql.txt" />
      <appendToFile value="true" />
      <layout type="log4net.Layout.PatternLayout">
         <conversionPattern value="%message%newline" />
      </layout>
    </appender>

  <logger name="YourDataContext">
      <level value="ALL" />
      <appender-ref ref="LinqFile" />
    </logger>
</log4net>

This is just enough to have Linq 2 SQL output saved in a text file. Just change level to OFF in XML config to disable L2S logging altogether.

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