具有Nullable DateTime属性的ASP.NET MVC4模型绑定问题

Question

I'm experiencing an issue with model binding which is happening outside the context of a controller action. I'm using the following code to handle the binding, and it's working in almost all scenarios, however, it seems to fall over on any properties that are of type "DateTime?". Does anyone have any ideas? In this instance TEntity is a POCO representing a blog post, so has a number of fields that are strings, longs etc. and these are all binding fine. It's just the optional datetimes (in this instance called "PublishStart" and "PublishEnd") that are failing to bind. The result that comes back from BindModel always has null values for these. The input in the form collection is always using the format "dd/MM/yyyy" for the datetime.

In stepping through the code in debug mode, I have tried using valueProvider.GetValue("PublishStart"), which doesn't throw any errors and shows what I'd expect for the RawValue, but I can't see how to get the value from that result to check whether it's parsed OK.

Code I'm using is below. Does anyone have any ideas?

var valueProvider = new NameValueCollectionValueProvider(formCollection, null);
var metadata = ModelMetadataProviders.Current.GetMetadataForType(null,
               typeof(TEntity));

var bindingContext = new ModelBindingContext
{
    ModelName = "",
    ValueProvider = valueProvider,
    ModelMetadata = metadata
    };

var controllerContext = new ControllerContext();
var binder = new DefaultModelBinder();

// act    
TEntity actual = (TEntity)binder.BindModel(controllerContext, bindingContext);

Global ASAX has the following to set the default model binder

System.Web.Mvc.ModelBinders.Binders.DefaultBinder = new DefaultModelBinder();

Answer 1

So a little digging yielded the answer here. Turns out someone had added a custom model binder for DateTimes that was causing this to return null. Moral of the story, look out for calls to Binders.Add.