How can I invoke a custom model binder in MVC4?

Question

So it seems like several people (like here and here) have had issues with MVC4 model binding for ApiControllers, but none of them seem to quite address the

Answer 1

If you're talking ApiControllers, then you're trying to model bind in Web API and now MVC Here's a sample model binder

  public class MyRequestModelBinderProvider : ModelBinderProvider
    {
        MyRequestModelBinder binder = new MyRequestModelBinder();
        public IdeaModelBinderProvider()
        {          
        }

        public override IModelBinder GetBinder(HttpActionContext actionContext, ModelBindingContext bindingContext)
        {
            if (bindingContext.ModelType == typeof(MyRequestModel))
            {
                return binder;
            }

            return null;
        }
    } 

Here's an example of registering a custom model binder provider

 IEnumerable<object> modelBinderProviderServices = GlobalConfiguration.Configuration.ServiceResolver.GetServices(typeof(ModelBinderProvider));
 List<Object> services = new List<object>(modelBinderProviderServices);
 services.Add(new MyRequestModelBinderProvider());
 GlobalConfiguration.Configuration.ServiceResolver.SetServices(typeof(ModelBinderProvider), services.ToArray());

Now in your custom model binder you use the contexts to access the querystring values

  public class MyRequestModelBinder :  IModelBinder
    {
        public MyRequestModelBinder()
        {

        }

        public bool BindModel(HttpActionContext actionContext, ModelBindingContext bindingContext)
        {
            MyRequestModel yourModel; 
            //use contexts to access query string values
            //create / update your model properties

            bindingContext.Model = yourModel;  
            //return true || false if binding is successful
        }

Make sure your using the classes and interfaces for WebAPI and not MVC. Some of the names are the same, but different namespaces and dlls