I'm working with the NerdDinner application trying to teach myself ASP.NET MVC. However, I have stumbled upon a problem with globalization, where my server presents floating point numbers with a comma as the decimal separator, but Virtual Earth map requires them with dots, which causes some problems.
I have already solved the issue with the mapping JavaScript in my views, but if I now try to post an edited dinner entry with dots as decimal separators the controller fails (throwing InvalidOperationException
) when updating the model (in the UpdateModel()
metod). I feel like I must set the proper culture somewhere in the controller as well, I tried it in OnActionExecuting()
but that didn't help.
I have just revisited the issue in a real project and finally found a working solution. Proper solution is to have a custom model binder for the type decimal
(and decimal?
if you're using them):
using System.Globalization;
using System.Web.Mvc;
public class DecimalModelBinder : DefaultModelBinder
{
public override object BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext)
{
object result = null;
// Don't do this here!
// It might do bindingContext.ModelState.AddModelError
// and there is no RemoveModelError!
//
// result = base.BindModel(controllerContext, bindingContext);
string modelName = bindingContext.ModelName;
string attemptedValue = bindingContext.ValueProvider.GetValue(modelName)?.AttemptedValue;
// in decimal? binding attemptedValue can be Null
if (attemptedValue != null)
{
// Depending on CultureInfo, the NumberDecimalSeparator can be "," or "."
// Both "." and "," should be accepted, but aren't.
string wantedSeperator = NumberFormatInfo.CurrentInfo.NumberDecimalSeparator;
string alternateSeperator = (wantedSeperator == "," ? "." : ",");
if (attemptedValue.IndexOf(wantedSeperator, StringComparison.Ordinal) == -1
&& attemptedValue.IndexOf(alternateSeperator, StringComparison.Ordinal) != -1)
{
attemptedValue = attemptedValue.Replace(alternateSeperator, wantedSeperator);
}
try
{
if (bindingContext.ModelMetadata.IsNullableValueType && string.IsNullOrWhiteSpace(attemptedValue))
{
return null;
}
result = decimal.Parse(attemptedValue, NumberStyles.Any);
}
catch (FormatException e)
{
bindingContext.ModelState.AddModelError(modelName, e);
}
}
return result;
}
}
Then in Global.asax.cs in Application_Start():
ModelBinders.Binders.Add(typeof(decimal), new DecimalModelBinder());
ModelBinders.Binders.Add(typeof(decimal?), new DecimalModelBinder());
Note that code is not mine, I actually found it at Kristof Neirynck's blog here. I just edited a few lines and am adding the binder for a specific data type, not replacing the default binder.