error with decimal in mvc3 - the value is not valid for field

I encountered this issue when developing a web application for an English audience, on a Pc in The Netherlands.

A model property of type double, generated this server-side validation error:

The value '1.5' is not valid for .

On an breakpoint, I saw these values in the Immediate Window:

?System.Threading.Thread.CurrentThread.CurrentUICulture

{en-US}

?System.Threading.Thread.CurrentThread.CurrentCulture

{nl-NL}

As a solution (or maybe a work-around), you can specify the globalization settings in the web.config file.

<configuration>
  <system.web>
    <globalization culture="en" uiCulture="en" />

Of course this means that you force your users to enter numbers in English formatting, but that is just fine, in my case.

I just stumbled on this again after 2 years. I thought ASP.NET MVC 5 had solved this but looks like it's not the case. So here goes how to solve the problem...

Create a class called DecimalModelBinder like the following and add it to the root of your project for example:

using System;
using System.Globalization;
using System.Web.Mvc;

namespace YourNamespace
{   
    public class DecimalModelBinder : IModelBinder
    {
        public object BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext)
        {
            ValueProviderResult valueResult = bindingContext.ValueProvider
                .GetValue(bindingContext.ModelName);

            ModelState modelState = new ModelState { Value = valueResult };

            object actualValue = null;

            if(valueResult.AttemptedValue != string.Empty)
            {
                try
                {
                    actualValue = Convert.ToDecimal(valueResult.AttemptedValue, CultureInfo.CurrentCulture);
                }
                catch(FormatException e)
                {
                    modelState.Errors.Add(e);
                }
            }

            bindingContext.ModelState.Add(bindingContext.ModelName, modelState);

            return actualValue;
        }
    }
}

Inside Global.asax.cs, make use of it in Application_Start() like this:

ModelBinders.Binders.Add(typeof(decimal?), new DecimalModelBinder());

You are one of the non-English customers, which MS has not foreseen. You will need to put some extra effort into making your version run. I had a similar problem, denying me both "9,99" and "9.99" as valid numbers. It seems like once server-side validation failed, and once client-side validation, causing no number to be accepted.

So you have to make the validation congruent.

Like suggested in the comments, have a look at http://msdn.microsoft.com/en-us/library/gg674880(VS.98).aspx and http://haacked.com/archive/2010/05/10/globalizing-mvc-validation.aspx and MVC 3 jQuery Validation/globalizing of number/decimal field or - should you understand German (or just look at the code examples) http://www.andreas-reiff.de/2012/06/probleme-mit-mvcmovies-beispiel-validierung-des-preises-mit-dezimalstellen-schlagt-fehl/

BTW, same problem exists for both the Music and Movie example tutorials.