ModelState is marked invalid for an empty non-required field

Question

A bit of a mystery. I have a viewmodel with a Year property: ``` public class TradeSpendingSalesViewModel { public string ProductCode { get; set; } public IEnumerable AllowTypeSelect { get; set; } public string AllowType { get; set; } public IEnumerable YearsSelect { get; set; } public int Year { get; set; } } ``` If I post an empty viewmodel to my controller: ``` [HttpPost] public ActionResult Index(TradeSpendingSalesViewModel vm) { var allErrors = ModelState.Values.SelectMany(v => v.Errors); foreach (var e in allErrors) { Response.Write(e.ErrorMessage); } } ``` Then I get a single error with a message of: "The Year field is required." Since I haven't annotated the viewmodel Year field with the `Required` attribute, I'm unclear why this error is being generated. Any ideas?

Accepted Answer

My first guess would be that it is throwing an exception that you're not setting year and it's null? if you made year a Nullable<int> does it not throw the required message?

I still wouldn't expect it to be required, it's a shot in the dark

ModelState is marked invalid for an empty non-required field

Solution

Problem