How to Implement The DataAnnotions in mvc for DropDown List

Question

 Hi All ,

 

  This Is model 

  [Required(ErrorMessage = " Please Select The Country Name.")]

public string CountryName { get; set; }

 

This is view 

@Html.DropDownListFor(m => m.CountryId, new SelectList(Model.CountryList, "Id", "Name"), new { @class = "form-control", placeholder = "Select Country", @autofocus = "autofocus" }) 

 

 

 

i try apply DataAnnonations   dropdown list , but not working Where Iam Doing please give suggestions