How can I control the attempted value for a custom model binder?

Question

I've got an action with a signature like this:

public ActionResult Index([ModelBinder(typeof(MyEnumModelBinder))] MyEnum myEnum)

Which is implemented like this:

public class MyEnumModelBinder: IModelBinder
{
   public object BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext)
   {
      var valueProviderResult = bindingContext.ValueProvider.GetValue("myEnum");
      return valueProviderResult == null ? 
         MyEnum.Default : 
         valueProviderResult.AttemptedValue.ToMyEnum();
   }
}

Basically, i'm binding a raw value to an enum, pretty simple. Works fine.

But, notice how in order to get access to the attempted value, i need to use a magic string ("myEnum").

Is there any way i can supply this to the model binder, so remove the magic string?

Because if i want to use this model binder in other places, then i have to make sure i call the parameter "myEnum", otherwise it will cause a runtime error.

I tried adding a ctor to the model binder, but there's nowhere where i actually instantiate it.

Any ideas?

I'm affraid there is no easy way out of this. What you're really asking is how to get the parameter name. Reflection simply doesn't expose this. — Polity, Feb 21 '12 at 03:09

score 1 · Accepted Answer · answered Feb 21 '12 at 07:16

1

Is there any way i can supply this to the model binder, so remove the magic string?

Sure:

var valueProviderResult = bindingContext.ValueProvider.GetValue(bindingContext.ModelName);

answered Feb 21 '12 at 07:16

Darin Dimitrov

1,023,142
271
3,287
2,928

How can I control the attempted value for a custom model binder?

1 Answers1