Question

I want to extend the default model binding to be more smart when dealing with numbers. The default works very bad when are commas and decimals points in the game.

I was trying the do a new binder

Public Class SmartModelBinder
    Inherits DefaultModelBinder
    Protected Overrides Sub SetProperty(controllerContext As ControllerContext, bindingContext As ModelBindingContext, propertyDescriptor As System.ComponentModel.PropertyDescriptor, value As Object)
        If propertyDescriptor.PropertyType Is GetType(Decimal) Or propertyDescriptor.PropertyType Is GetType(Decimal?) Then
            If value Is Nothing Then
                value = 0
            End If
        End If

        MyBase.SetProperty(controllerContext, bindingContext, propertyDescriptor, value)
    End Sub
End Class

But the value is already converted at this point

How can I extend the binder to get the string value from the form and perform a different transformation?

Answer 1

What about this?

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

And a custom binder. I guess I don’t know if you can override decimal binding in this way, but it works for my own types.

public class DecimalModelBinder : DefaultModelBinder
{
    public override object BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext)
    {
        var valueProviderResult = bindingContext.ValueProvider.GetValue(bindingContext.ModelName);
        if (valueProviderResult == null)
        {
            return base.BindModel(controllerContext, bindingContext);
        }
        // to-do: your parsing (get the text value from valueProviderResult.AttemptedValue)
        return parsedDecimal;
    }
}