Set required to select validation for dropdown list in asp.net razor

Question

How can I apply the selection required validation on dropdownlist in asp.net razor without using model. below is my DropDownList

<td>@Html.DropDownList("Units", new SelectList(@ViewBag.Settings.CdcPortalRentInfo 
         , "CdcPortalRentInfoId" , "Description")
         , new { style = "width:250px" })
</td>

Answer 1

In your model just add data annotation :

 [Required(ErrorMessage = "You must select a RentInfo")]
    public int CdcPortalRentInfoId{ get; set; }
    public int Description{ get; set; } //I think this is you property

Answer 2

try something like this with required attribute in MVC

public class CdcPortalRentInfo 
{
      [Required(ErrorMessage="Your Error Message")]
      public int CdcPortalRentInfoId{ get; set; }

       public string Description {get;set;}
}