Modelmetadata additional values always empty MVC4 - asp.net-mvc-4

Question

I have the below property in my model:
[Required]
[UIHint("DropDownList")]
[AdditionalMetadata("Source", "Party.Organization.Caption")]
public int PartyId { get; set; }
I am trying to get the additional metadata value in view as follows:
object s = ViewData.ModelMetadata.AdditionalValues["Source"];
but it is always returning count 0.
not sure, why, can somebody advise pls?
complete view:
#model IEnumerable<object>
#using System.Reflection;
#using r2d2Web.Extensions;
#using d2Utils.Extensions.d2Type;
#using d2Utils.Reflection;
#using System.Collections;
#{
Type mdlType = Model.First().GetType();
PropertyInfo keyProp = mdlType.GetKeyProperty();
IEnumerable<PropertyInfo> props = mdlType.EditorProps();
Hashtable parties = (Hashtable)ViewData["Parties"];
Hashtable partyroles = (Hashtable)ViewData["Partyroles"];
}
<div class="grid">
<table>
<thead>
<tr>
#foreach (var prop in props)
{
<th>#prop.Name</th>
}
<th></th>
</tr>
</thead>
<tbody>
#foreach (var obj in Model)
{
<tr>
#foreach (var prop in props)
{
if (prop.Name == "PartyId")
{
object s = ViewData.ModelMetadata.AdditionalValues["Source"];
<td>#(obj.GetValForProp<string>(s.ToString()))</td>
}
else if (prop.Name == "PartyRoleTypeId")
{
<td>#partyroles[obj.GetValForProp<int>(prop.Name)]</td>
}
else
{
<td>#(obj.GetValForProp<string>(prop.Name))</td>
}
}
<td>
#Html.ActionLink("Edit", "Edit", new { id = obj.GetValForProp<int>(keyProp.Name) }) |
</td>
</tr>
}
</tbody>
</table>
</div>
<div id="my-dialog"></div>

Answer 1

You are not specifying field for getting additional metadata. Try to do it like this:
#ViewData.ModelMetadata.Properties.FirstOrDefault(n => n.PropertyName == "PartyId").AdditionalValues["Source"]
If you had strongly typed view model with type that contains PartyId better option would be to use
#ModelMetadata.FromLambdaExpression(x => x.PartyId, ViewData).AdditionalValues["Source"]