log4net如何获取Log错误的输出？

Question

I have ac# web application and I would like to be able to see errors being thrown in the Service.asmx.cs section. Ie when the sql statement fails or I spelled a variable name wrong.. etc. I'm fairly new to .net but the template for the app that I have has log4net installed.

 protected static log4net.ILog Log = EarthSoft.Common.log4net.GetLogger(typeof (Service));

Then my get method is :

   [WebMethod(Description = "Get a list of facilities")]

public List<Facility> GetFacilities() 
{
  try
  {
    var context = EarthSoft.Server.Helpers.RequestContext.GetRequestContext(true);

    if (context.Connection == null || context.User == null) return null;

    var lst = new List<Facility>();

    string sql =

       string.Format("select analyte_full,conc from dt_biological");

    var cmd = context.Connection.CreateCommand(sql);
    context.Connection.PrepareTextCommand(cmd);
    using (var reader = cmd.ExecuteReader())
    {
      while (reader.Read())
      {
        lst.Add(new Facility()
          {

            name = (string)reader.GetValue(0),
            distance  = (decimal)reader.GetValue(1)
        });
      }
    }
    context.Connection.Close();

    return lst;
  }
  catch (Exception ex)
  {
    Log.Error(ex.Message, ex);
    return null;
  }
}

So the error message is appended to the Log here but I have no idea how to access it or where it writes the log? Is it possible the log output is saved onto a table into the sql database somewhere?

Answer 1

Log4Net is higly configurable, and to specify "where" to log, it uses the "appender" concepts. There is a lot of appender already done that write in files/database/queues and you can write your own, if needed ( normally not ). Anyway start to look at the examples from here: https://logging.apache.org/log4net/release/config-examples.html Somewher ein your code, typically in the application initialization, you have to call:

XmlConfigurator.Configure()

This will read the configuration from the application configuration file. Alternatively you can configure log4net programmatically, but it can be sort of advanced if you never used before with manual configuration, so I suggest to start looking at the examples above and use configuration from file. If no configuration is supplied, log4net work perfectly but... no log are produced at all, and I think this is the reason you can't find any log at the moment.