title: Why won't my Edit screen validation allow null?
body: <p>I added a field to a view model for a <code>Document</code> that should allow the user to associate it with a <code>Tenant</code>. It works fine if the user does assign a tenant, but if they select the null option from the dropdown, then the validation tells me that "The ItemID field is required.", where <code>ItemID</code> is a field on <code>TenantViewModel</code>.</p>
  
  <p>It occurs to me that perhaps I'm using editor templates wrong - I'm trying to select from a list of tenants, not edit a tenant. If that's wrong, let me know, and maybe suggest a better way to get the dropdown.</p>
  
  <pre><code>namespace TenantPortal.Models
  {
      public class DocumentViewModel
      {
          ...
  
          [UIHint("SelectTenant")]
          public TenantViewModel Tenant { get; set; }
       }
  
      public class TenantViewModel
      {
          private Tenant _ten = null;
  
          public int ItemID { get; set; }
  
          public string Display_Name { get; set; }
  
          public string Legal_Name { get; set; }
  
          ...
      }
  }
  </code></pre>
  
  <p>Editor Template: SelectTenant.cshtml</p>
  
  <pre><code>@using CMS.DocumentEngine.Types.Tenantportal
  @using TenantPortal.Models
  @model TenantViewModel
  
  @{ 
      Layout = null;
  
      var opts = new SelectList(TenantProvider.GetTenants(), "ItemID", "Display_Name");
  }
  
  @Html.DropDownListFor(model =&gt; model.ItemID, opts, "(none)")
  </code></pre>