如何在運行時在expando上添加對象屬性？

Question

我讀了一些關於expando對象here的文章，但我想實現不同的事情。
我想在運行時動態屬性添加屬性對象，把它的值，然後在以後檢索：

private static readonly ConditionalWeakTable<object, ExpandoObject> props = new ConditionalWeakTable<object, ExpandoObject>(); 
    public static void AddDataExtension(this object key, dynamic value) 
    { 
     props.Add(key, value); 
    } 

    public static dynamic GetDataExtension(this object key) 
    { 
     ExpandoObject ex = null; 
     return props.TryGetValue(key, out ex); 
    } 

用法：

'Insert data at runtime' 
instance.AddDataExtension("Hello", "hi"); 

'Get the data at runtime' 
instance.GetDataExtension("Hello") 

但我收到此錯誤：

The best overloaded method match for 'System.Runtime.CompilerServices.ConditionalWeakTable<object,System.Dynamic.ExpandoObject>.Add(object, System.Dynamic.ExpandoObject)' has some invalid arguments 

我想我濫用了這個屬性，這是可能實現的嗎？如果是的話，怎麼樣？請幫忙。

編輯

這裏是完整的類：

public static class instance 
{ 
    private static readonly ConditionalWeakTable<object, ExpandoObject> props = new ConditionalWeakTable<object, ExpandoObject>(); 
     public static void AddDataExtension(this object key, dynamic value) 
     { 
      props.Add(key, value); 
     } 

     public static dynamic GetDataExtension(this object key) 
     { 
      ExpandoObject ex = null; 
      return props.TryGetValue(key, out ex); 
     } 
} 

我想實現的是：
我會隨機varialbes，例如， 「photo_01, photo_12, photo_15, name_01, name_02, age_01, age_02」
如果可能的話我想用這種方法使用該方法：

id = <fetch from dbase> 
instance.AddDataExtension("photo_" + id, byte[]); 

，然後檢索值：

instance.GetDataExtension("photo_" + id) 

Answer 1

因爲ExpandoObject是密封的，是不可能的。

Answer 2

我沒有看到你從ExpandoObject繼承所以你可能需要做的。 ExpandoObject具有很好的基礎結構，您可以使用它來創建動態類型。

下面是去詳細瞭解創建動態類型的文章： http://www.codeproject.com/Articles/62839/Adventures-with-C-4-0-dynamic-ExpandoObject-Elasti

Answer 3

使用conditionalWeakTable和動態，你可以在幾行實現動態擴展屬性：

using System.Dynamic; 
using System.Runtime.CompilerServices; 

namespace ExtensionProperties 
{ 
    /// <summary> 
    /// Dynamically associates properies to a random object instance 
    /// </summary> 
    /// <example> 
    /// var jan = new Person("Jan"); 
    /// 
    /// jan.Age = 24; // regular property of the person object; 
    /// jan.DynamicProperties().NumberOfDrinkingBuddies = 27; // not originally scoped to the person object; 
    /// 
    /// if (jan.Age &lt; jan.DynamicProperties().NumberOfDrinkingBuddies = 27) 
    /// Console.WriteLine("Jan drinks too much"); 
    /// </example> 
    /// <remarks> 
    /// If you get 'Microsoft.CSharp.RuntimeBinder.CSharpArgumentInfo.Create' you should reference Microsoft.CSharp 
    /// </remarks> 
    public static class ObjectExtensions 
    { 
     ///<summary>Stores extended data for objects</summary> 
     private static ConditionalWeakTable<object, object> extendedData = new ConditionalWeakTable<object, object>(); 

     /// <summary> 
     /// Gets a dynamic collection of properties associated with an object instance, 
     /// with a lifetime scoped to the lifetime of the object 
     /// </summary> 
     /// <param name="obj">The object the properties are associated with</param> 
     /// <returns>A dynamic collection of properties associated with an object instance.</returns> 
     public static dynamic DynamicProperties(this object obj) => extendedData.GetValue(obj, _ => new ExpandoObject()); 
    } 
} 

的利用方法是在XML註釋：

var jan = new Person("Jan"); 

jan.Age = 24; // regular property of the person object; 
jan.DynamicProperties().NumberOfDrinkingBuddies = 27; // not originally scoped to the person object; 

if (jan.Age && jan.DynamicProperties().NumberOfDrinkingBuddies == 27) 
{ 
    Console.WriteLine("Jan drinks too much"); 
}