DataAnnotations on public fields vs properties in MVC

Question

Why don't DataAnnotations work on public fields? Example:

namespace Models
{
    public class Product
    {
        [Display(Name = "Name")]
        public string Title; // { get; set; }
    }
}

public ActionResult Test()
{
     return View(new Models.Product() { Title = "why no love?" });
}

@Html.LabelFor(m => m.Title) // will return 'Title' if field, or 'Name' if property
@Html.DisplayFor(m => m.Title)

If Title is a field, then the Display attribute seems to have no effect. If Title is changed to a property, it works as expected as displays "Name".

It would seem easy in this example to just change to a property, but I am trying to use the types from F# where they get compiled to a class with fields and not properties.

This was tested in ASP.NET 4 and MVC RC 3.

Answer 1

The reason why DataAnnotations do not work with fields is because the reflection-like mechanism that is used to retrieve the attributes (TypeDescriptor) only supports properties.

While it would not be easy, we could look into making this work with fields if there is enough demand.