How to Watch Linq Expressions in VS 2015

Question

I am trying to debug a Linq expression in Visual Studio 2015. When I add it to the watch window I get the following error in the Value column.

field.DomainValues.Where(d => d.Active) error CS1061: 'List' does not contain a definition for 'Where' and no extension method 'Where' accepting a first argument of type 'List' could be found (are you missing a using directive or an assembly reference?)

When I try to execute in the Immediate Window I get the same error.

error CS1061: 'List' does not contain a definition for 'Where' and no extension method 'Where' accepting a first argument of type 'List' could be found (are you missing a using directive or an assembly reference?)

I thought that support was added for this in Visual STudio 2015 based on this article - http://blogs.msdn.com/b/visualstudioalm/archive/2014/11/12/support-for-debugging-lambda-expressions-with-visual-studio-2015.aspx

I found this article that outlines some limitations, but none apply to my x86 WPF application. http://dotnetdeewane.blogspot.com/2015/03/support-for-debugging-lambda.html

• I have an x86 .Net 4.5 WPF app
• In my output window I see that System.Core has been loaded.

Loaded 'C:\WINDOWS\Microsoft.Net\assembly\GAC_MSIL\System.Core\v4.0_4.0.0.0__b77a5c561934e089\System.Core.dll'

• My method is static and not async. I do have the using System.Linq statement at the top of my class.

  using Infragistics.Windows.Editors;
  using Microsoft.Practices.ServiceLocation;
  using System;
  using System.Collections.Generic;
  using System.Linq;
  using System.Windows;
  
  public static ValueEditor SelectEditor(ColumnConfig config, TableInfo info, object value = null)    
  {    
      //do some stuff    
      field.FilteredDomainValues = field.DomainValues.Where(d => d.Active).ToList();    
      //do some other stuff    
  }
  

• I'm not using dynamic types

I have Visual Studio 2012 and Visual Studio 2013 also installed.

I am using Resharper.

Anything else I could check in VS options?

Answer 1

The key is to ensure that System.Core.dll is loaded. One easy way to do this is to have the following at the top of the file you're debugging in:

#if DEBUG
using System.Diagnostics;
#endif

Answer 2

I had the same problem and i fixed it making a call to Enumerable.Range in the code before checking the lambda expression in the watching window