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Asked: 2020-04-07 09:05:11 +0800 CST 2020-04-07 09:05:11 +0800 CST

Why doesn't this extension method work?

  • 772

Extension method:

namespace PantallaHornosApp
{
 public static class ExceptionHelper
 {
    public static string GetErrorDetails(this Exception ex)
    {
        StringBuilder sb = new StringBuilder();
        sb.AppendFormat("Error: {0}", ex.InnerException);
        Exception innerExc = ex.InnerException;
        int level = 1;
        while (innerExc != null)
        {
            if (!string.IsNullOrWhiteSpace(innerExc.Message))
            {
                sb.AppendFormat("Inner Exception {0}: {1}", new[] { level.ToString(), innerExc.Message });
            }
            innerExc = innerExc.InnerException;
            level++;
        }
        sb.AppendFormat("Stack trace: {0}", ex.StackTrace);
        sb.AppendFormat("Target site: {0}", ex.TargetSite);
        sb.AppendFormat("Source: {0}", ex.Source);
        return sb.ToString();
    }
 }
}

I want to call it like this:

namespace PantallaHornosApp
{
 public class PartesController : ApiController
 {

    public IHttpActionResult Post(Parte parte)
    {
        try
        {
            using (HornosContext db = new HornosContext())
            {
                db.Partes.Add(parte);
                int res = db.SaveChanges();
            }


            return Ok();
        }
        catch (Exception ex)
        {
            //ERROR
            //Error 1   'System.Exception' does not contain a definition for 'GetErrorDetails' and no extension method 'GetErrorDetails' accepting a first argument of type 'System.Exception' could be found (are you missing a using directive or an assembly reference?) c:\users\atorres\proyectos\pantallashornos\pantallahornosapp\api\partescontroller.cs    51  37  PantallaHornosApp

            Trace.TraceError(ex.GetErrorDetails());
            return InternalServerError(ex);
        }

    }
 }
}
  • Intellisence doesn't identify it for me.
  • They are in the same namespace
  • The extension class and method are static
  • I am using the word "this"
  • Everything is in the same project
  • I already restarted visual studio
  • I already removed and re-added the project in the solution
  • I already gave it clean - rebuild

The problem has to do with the namespace and not with the Exception type, I made an extension method for String and it doesn't find it either

What's going on?

c#

2 Answers

  1. Best Answer
    1. I disabled Web Essentials 2013.5
    2. I restarted VS , it still didn't work, but I don't know if disabling Web Essentials helped anything
    3. I copied the code of the extension method and pasted it in a new file, I deleted the original
    4. I restarted VS and it worked

    Bonus: I re-enabled Web Essentials and the problem did not recur.

    • 2

  2. Put the corresponding using in the class where you want to invoke it.

    using PantallaHornosApp;

    In the help ( https://msdn.microsoft.com/es-co/library/bb383977.aspx ) it says the following:

    Extension methods are only in scope when the namespace is explicitly imported in the source code with a using directive.

    • 1