Web API空導航屬性

Question

我在嘗試展開模型中對象的導航屬性時出現錯誤。

eg. /odata/Products?$expand=ProductDetails 

我收到以下錯誤：

No NavigationLink factory was found for the navigation property 'ProductDetails' from entity type 'ProductModels.Models.Product' on entity set 'Products'. Try calling HasNavigationPropertyLink on the EntitySetConfiguration. 

參數名：navigationProperty

我的模型看起來是這樣的：

public class Person 
{ 
    public int Id { get; set; } 

    public string Name { get; set; } 
    [ForeignKey("Name")] 
    public PersonDetails PersonDetails { get; set; } 
} 

public class PersonDetails 
{ 
    [Key] 
    public string FullName { get; set; } 

    public int Age { get; set; } 

} 

它是一個零/一對一的關係你可以看到我的模型有點奇怪，PersonDetails通過Person關聯到Person.Name = PersonDetails .FullName但實體框架6不處理它，並生成如下的SQL：

SELECT 
[Extent1].[Id] AS [Id], 
N'f4243347-5b4c-4790-a07d-e8beb80bea72' AS [C1], 
[Extent1].[Name] AS [Name], 
N'PersonDetails' AS [C2], 
N'f4243347-5b4c-4790-a07d-e8beb80bea72' AS [C3], 
[Extent2].[FullName] AS [FullName], 
[Extent2].[Age] AS [Age], 
CASE WHEN ([Extent1].[Name] IS NULL) THEN cast(1 as bit) ELSE cast(0 as bit) END AS [C4] 
FROM [Persons] AS [Extent1] 
LEFT OUTER JOIN [PersonDetails] AS [Extent2] ON [Extent1].[Name] = [Extent2].[FullName] 

而在結果，許多產品詳細記錄是零，這是確定的。

但似乎OData格式化程序有一個問題，其中Person.Name爲空。我有以下我ProductsContext設置：

public System.Data.Entity.DbSet<Product> Products { get; set; 

這ODataConventionModelBuilder：

builder.EntitySet<Vehicle>("Products"); 

我沒有對產品詳細的控制，因爲我不想直接訪問它，只有通過產品控制器。

如果我添加在：

builder.EntitySet<Vehicle>("ProductDetails"); 

然後我得到一個：

The EDM instance of type '[ProductModels.Models.ProductDetails Nullable=True]' is missing the property 'FullName'. 

這是有道理的，因爲全名很可能在該產品詳細記錄空。

我可以看到的唯一方法是使用HasNavigationPropertyLink，而不是像上面那樣構建ProductDetails的標準方式。

任何人都可以給我任何建議我應該做什麼？

Answer 1

試試這個代碼片段：

var products=builder.EntitySet<Vehicle>("Products"); 
    products.HasNavigationPropertiesLink(
       product.NavigationProperties, 
       (entityContext, navigationProperty) => 
       { 
        object id; 
        entityContext.EdmObject.TryGetPropertyValue("ID", out id); 
        return new Uri(entityContext.Url.Link(ODataTestConstants.DefaultRouteName, 
       new 
       { 
        odataPath = entityContext.Url.CreateODataLink(
         new EntitySetPathSegment(entityContext.NavigationSource.Name), 
         new KeyValuePathSegment(id.ToString()), 
         new NavigationPathSegment(navigationProperty)) 
       })); 
       }, true); 

Answer 2

到ODataConfig.cs加入實體的條目下。

builder.EntitySet<EntityName>(typeof(EntityName).Name); 

，整個代碼會是這樣

public static class ODataConfig 
    { 
     public static void Register(HttpConfiguration config) 
     { 
      ODataModelBuilder builder = new ODataConventionModelBuilder(); 
      builder.EntitySet<EntityName>(typeof(EntityName).Name); 
      var model = builder.GetEdmModel(); 
      config.Routes.MapODataRoute("odata", "odata", model); 

      config.EnableQuerySupport(); 
     } 
    } 

Answer 3

這爲我工作：

foreach (var navProp in products.EntityType.NavigationProperties) 
      { 
products.HasNavigationPropertyLink(
      navprop, 
      (entityContext, navigationProperty) => 
      { 
       object id; 
       entityContext.EdmObject.TryGetPropertyValue("ID", out id); 
       return new Uri(entityContext.Url.CreateODataLink(
        new EntitySetPathSegment(navprop.Name), 
        new KeyValuePathSegment(id.ToString()) 
        )); 
      }, false); 
}