的自定義數據類型的類不顯示

我有一個CustomProductProperty模式，讓用戶擁有自己的產品自定義字段，內包含鏈接到處理用戶定義的數據類型數據庫CustomDataType模型。的自定義數據類型的類不顯示

[Table("Product")] 
public class Product 
{ 
    [Key] 
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)] 
    public int ProductID { get; set; } 
    public int ProductTypeID { get; set; } 
    [Display(Name = "Product Name")] 
    public string ProductName { get; set; } 
    [ForeignKey("ProductTypeID")] 
    [Display(Name = "Product Type")] 
    public virtual ProductType ProductType { get; set; } 
    public virtual ICollection<CustomProductProperty> CustomProperties { get; set; } 
} 

[Table("CustomProductProperty")] 
public class CustomProductProperty 
{ 
    [Key] 
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)] 
    public int CustomPropertyID { get; set; } 

    public int CustomDataTypeID { get; set; } 
    [ForeignKey("CustomDataTypeID")] 
    public virtual CustomDataType DataType { get; set; } 

    public int ProductID { get; set; } 
    [ForeignKey("ProductID")] 
    public virtual Product Product { get; set; } 

    public string PropertyValue { get; set; } 
} 

[Table("CustomDataType")] 
public class CustomDataType 
{ 
    [Key] 
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)] 
    public int CustomTypeID { get; set; } 
    public string PropertyName { get; set; } 
    public CustomDataTypes DataType { get; set; } 
    public int ModuleID { get; set; } 
    [ForeignKey("ModuleID")] 
    public Module Module { get; set; } 
}

當試圖在我看來，以顯示這一點，我創建了一個顯示模板來處理CustomProductProperty的ICollection的<>出於某種原因，DataType.PropertyName是空的，但PropertyValue仍返回正確的數據，有人知道爲什麼PropertyName是空的？

@model IEnumerable<InventoryManager.Models.CustomProductProperty> 
@{ 
    Layout = null; 
} 
@foreach (var item in Model) 
{ 
<tr> 
    <th>@Html.DisplayFor(model => item.DataType.PropertyName)</th> 
    <td>@Html.DisplayFor(model => item.PropertyValue)</td> 
</tr>  
}

來源

2013-06-18 ChaoticLoki