WCF 中的動態 ExpandoObject

Question

嘗試通過枚舉類型進程和動態數據的操作來 Ping/Pong 我的服務。

[ServiceContract ( CallbackContract = typeof ( iStackoverflowCallBack ) )]
public interface iStackoverflow
{
    [OperationContract]
    void Ping ( Process Operation , dynamic Data );
}

[ServiceContract ( )]
public interface iStackoverflowCallBack
{
    [OperationContract]
    void Pong ( Process Operation , dynamic Data );
}

為什么這個服務有連接問題？

• 在實現兩個接口時， dynamic自動轉換為object 。
• 當從消費者ping我的服務時，ping 根本沒有到達服務，但服務正常工作。

---

解決方案 ：

[DataContract]
public class SerializableDynamicObject : IDynamicMetaObjectProvider
{
    [DataMember]
    private IDictionary<string,object> dynamicProperties = new Dictionary<string,object>();

    #region IDynamicMetaObjectProvider implementation
    public DynamicMetaObject GetMetaObject (Expression expression)
    {
        return new SerializableDynamicMetaObject(expression, 
            BindingRestrictions.GetInstanceRestriction(expression, this), this);
    }
    #endregion

    #region Helper methods for dynamic meta object support
    internal object setValue(string name, object value) 
    {
        dynamicProperties.Add(name, value);
        return value;
    }

    internal object getValue(string name) 
    {
        object value;
        if(!dynamicProperties.TryGetValue(name, out value)) {
            value = null;
        }
        return value;
    }

    internal IEnumerable<string> getDynamicMemberNames() 
    {
        return dynamicProperties.Keys;
    }
    #endregion
}


public class SerializableDynamicMetaObject : DynamicMetaObject
{
    Type objType;

    public SerializableDynamicMetaObject(Expression expression, BindingRestrictions restrictions, object value) 
        : base(expression, restrictions, value) 
    {
        objType = value.GetType();
    }

    public override DynamicMetaObject BindGetMember (GetMemberBinder binder)
    {
        var self = this.Expression;
        var dynObj = (SerializableDynamicObject)this.Value;
        var keyExpr = Expression.Constant(binder.Name);
        var getMethod = objType.GetMethod("getValue", BindingFlags.NonPublic | BindingFlags.Instance);
        var target = Expression.Call(Expression.Convert(self, objType),
                                     getMethod,
                                     keyExpr);
        return new DynamicMetaObject(target,
            BindingRestrictions.GetTypeRestriction(self, objType));
    }

    public override DynamicMetaObject BindSetMember (SetMemberBinder binder, DynamicMetaObject value)
    {
        var self = this.Expression;
        var keyExpr = Expression.Constant(binder.Name); 
        var valueExpr = Expression.Convert(value.Expression, typeof(object));
        var setMethod = objType.GetMethod("setValue", BindingFlags.NonPublic | BindingFlags.Instance);
        var target = Expression.Call(Expression.Convert(self, objType),
        setMethod, 
        keyExpr, 
        valueExpr);
        return new DynamicMetaObject(target,
            BindingRestrictions.GetTypeRestriction(self, objType));
    }

    public override IEnumerable<string> GetDynamicMemberNames ()
    {
        var dynObj = (SerializableDynamicObject)this.Value;
        return dynObj.getDynamicMemberNames();
    }
}

Answer 1

任何 WCF 操作協定的參數必須是 WCF 數據協定（或原始類型），否則數據將不會被序列化和傳輸。

http://msdn.microsoft.com/en-us/library/ms733127.aspx

Answer 2

擴展 Ahmed 的解決方案，了解如何使用它。

答案取自此頁面： https : //loosexaml.wordpress.com/2011/01/01/wcf-serialization-of-dlr-dynamic-types/

[DataContract]
public class SerializableDynamicObject : IDynamicMetaObjectProvider
{
    [DataMember]
    private IDictionary<string,object> dynamicProperties = new Dictionary<string,object>();

    #region IDynamicMetaObjectProvider implementation
    public DynamicMetaObject GetMetaObject (Expression expression)
    {
        return new SerializableDynamicMetaObject(expression, 
            BindingRestrictions.GetInstanceRestriction(expression, this), this);
    }
    #endregion

    #region Helper methods for dynamic meta object support
    internal object setValue(string name, object value) 
    {
        dynamicProperties.Add(name, value);
        return value;
    }

    internal object getValue(string name) 
    {
        object value;
        if(!dynamicProperties.TryGetValue(name, out value)) {
            value = null;
        }
        return value;
    }

    internal IEnumerable<string> getDynamicMemberNames() 
    {
        return dynamicProperties.Keys;
    }
    #endregion
}


public class SerializableDynamicMetaObject : DynamicMetaObject
{
    Type objType;

    public SerializableDynamicMetaObject(Expression expression, BindingRestrictions restrictions, object value) 
        : base(expression, restrictions, value) 
    {
        objType = value.GetType();
    }

    public override DynamicMetaObject BindGetMember (GetMemberBinder binder)
    {
        var self = this.Expression;
        var dynObj = (SerializableDynamicObject)this.Value;
        var keyExpr = Expression.Constant(binder.Name);
        var getMethod = objType.GetMethod("getValue", BindingFlags.NonPublic | BindingFlags.Instance);
        var target = Expression.Call(Expression.Convert(self, objType),
                                     getMethod,
                                     keyExpr);
        return new DynamicMetaObject(target,
            BindingRestrictions.GetTypeRestriction(self, objType));
    }

    public override DynamicMetaObject BindSetMember (SetMemberBinder binder, DynamicMetaObject value)
    {
        var self = this.Expression;
        var keyExpr = Expression.Constant(binder.Name); 
        var valueExpr = Expression.Convert(value.Expression, typeof(object));
        var setMethod = objType.GetMethod("setValue", BindingFlags.NonPublic | BindingFlags.Instance);
        var target = Expression.Call(Expression.Convert(self, objType),
        setMethod, 
        keyExpr, 
        valueExpr);
        return new DynamicMetaObject(target,
            BindingRestrictions.GetTypeRestriction(self, objType));
    }

    public override IEnumerable<string> GetDynamicMemberNames ()
    {
        var dynObj = (SerializableDynamicObject)this.Value;
        return dynObj.getDynamicMemberNames();
    }
}

一個簡單的使用方法：

dynamic d = new SerializableDynamicObject();
d.Name = “SomeData”;

d.Address = new SerializableDynamicObject();
d.Address.Line1 = “123 Spring St.”;

dynamic a = new SerializableDynamicObject();
a.Items = new List(new object[] { d, d });

return a;

但是請記住，WCF 需要了解數據類型，因為它是最基本的數據類型，如string 、 int等，這不是問題。 但是，如果您在動態對象中使用自定義數據類型，則必須使用[KnownType(typeof(XXX))]指令進行定義。 這適用於enums 、 List<>和任何其他自定義類。

例如：

[KnownType(typeof(MyCustomEnum))]
[KnownType(typeof(List<object>))]
[DataContract]
public class SerializableDynamicObject : IDynamicMetaObjectProvider
...