How to use data annotations for drop-down lists?

Question

In MVC3 data annotations can be used to speed up the UI development and validations; ie.

    [Required]
    [StringLength(100, ErrorMessage = \"The {0} must          


        

Answer 1

If you want to enforce the selection of an element in the DropDown use the [Required] attribute on the field you are binding to:

public class MyViewModel
{
    [Required]
    [Display(Name = "")]
    public string Continent { get; set; }

    public IEnumerable Continents { get; set; }
}

and in your view:

@Html.DropDownListFor(
    x => x.Continent, 
    Model.Continents, 
    "-- Select a continent --"
)
@Html.ValidationMessageFor(x => x.Continent)