Question

I’ve just updated to VS2010 (rc) and subsequently been forced to update my projects and convert to MVC2 (ta microsoft)… which has scuppered the first app its touched.

Error   2   'System.Web.Mvc.IValueProvider' does not contain a definition for
'Where' and no extension method 'Where' accepting a first argument of type 
'System.Web.Mvc.IValueProvider' could be found (are you missing a using directive or an 
assembly reference?)    ~\Controllers\DiscountsController.cs    51  39  ODSe

Considering I know this works in VS2008 – MVC1 I’m a tad thrown. Anyone?

I currently have (included)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;
using System.Web.Mvc.Ajax;
using ODSe.Models;
using System.Text;
using System.Text.RegularExpressions;
using System.Net.Mail;

Shouldnt need to be .net 4 as the original project was 3.5; and MVC2 is .net 3.5
(ASP.NET MVC 2 RC 2 provides a new Model-View-Controller (MVC) framework on top of the existing ASP.NET 3.5 SP1 runtime.)

Code Around 51

foreach (var x in this.ValueProvider.Where(k => k.Key.StartsWith("discount.")))
{
   if (String.IsNullOrEmpty(x.Value.AttemptedValue))
   {
     ModelState.SetModelValue(x.Key, new ValueProviderResult(ValueProvider[x.Key].AttemptedValue, collection[x.Key], System.Globalization.CultureInfo.CurrentCulture));
                        Discount = true;
   }
}

When the code was written for MVC(1) in VS2008 this.ValueProvider was “IDictionary ControllerBase.ValueProvider.
In MVC(2) VS2010 it throws a hissy fit about using where though this is apparently fine.

foreach (var x in this.ValueProvider)
                    {
                        if (x.Key.StartsWith("discount."))
                        {
                            if (String.IsNullOrEmpty(x.Value.AttemptedValue))
                            {
                                ModelState.SetModelValue(x.Key, new ValueProviderResult(ValueProvider[x.Key].AttemptedValue, collection[x.Key], System.Globalization.CultureInfo.CurrentCulture));
                                Discount = true;
                            }
                        }
                    }

If not a butt ugly piece of code; Legacy Code is soooo much fun

Answer 1

IValueProvider does not extend IEnumerable<T>, so LINQ extension methods like Where won’t be available.

IValueProvider is new in MVC 2, so it’s possible that you are accessing a property that was IEnumerable<T> in MVC 1.

Can you provide the code at NewDiscountsController.cs 51?