暴露的ExpandoObject的性质(Exposing properties of an Expa

我已经得到了我发送给外部库方法，它接受一个对象的ExpandoObject。 从我所看到的这个外部的lib使用TypeDescriptor.GetProperties内部这似乎会导致一些问题，我ExpandoObject。

我可以用一个匿名对象而不是去这似乎工作，但它更方便，我使用的ExpandoObject。

我需要构建自己的DynamicObject并通过实现ICustomTypeDescriptor还是我失去了一些东西照顾它自己。

想法？

---

更新

除了通过以下somedave（按照评论）的答案，我加入这个类

public class ExpandoObjectTypeDescriptionProvider : TypeDescriptionProvider
{
    private static readonly TypeDescriptionProvider m_Default = TypeDescriptor.GetProvider(typeof(ExpandoObject));

    public ExpandoObjectTypeDescriptionProvider()
        :base(m_Default)
    {
    }

    public override ICustomTypeDescriptor GetTypeDescriptor(Type objectType, object instance)
    {
        var defaultDescriptor = base.GetTypeDescriptor(objectType, instance);

        return instance == null ? defaultDescriptor :
            new ExpandoObjectTypeDescriptor(instance);
    }
}

并注册它是这样的：

dynamic parameters = new ExpandoObject();
TypeDescriptor.AddProvider(new ExpandoObjectTypeDescriptionProvider(), parameters);

Answer 1:

实际执行ICustomTypeDescriptor是不是所有的辛苦。 下面是我改编自一些工作，我与WinForms的属性网格（使用TypeDescriptor和PropertyDescriptor的）一些示例代码。 诀窍是，也能实现适当的PropertyDescriptor类，您可以从回传ICustomTypeDescriptor.GetProperties() 值得庆幸的ExpandoObject使得这个非常简单的通过实施IDictionary<string, object>为它的键和值的动态检索。 请记住，这可能会或可能无法正常工作（我没有测试过），它可能不会用大量的嵌套属性的ExpandoObjects工作。

public class ExpandoTypeDescriptor : ICustomTypeDescriptor
{
    private readonly ExpandoObject _expando;

    public ExpandoTypeDescriptor(ExpandoObject expando)
    {
        _expando = expando;
    }

    // Just use the default behavior from TypeDescriptor for most of these
    // This might need some tweaking to work correctly for ExpandoObjects though...

    public string GetComponentName()
    {
        return TypeDescriptor.GetComponentName(this, true);
    }

    public EventDescriptor GetDefaultEvent()
    {
        return TypeDescriptor.GetDefaultEvent(this, true);
    }

    public string GetClassName()
    {
        return TypeDescriptor.GetClassName(this, true);
    }

    public EventDescriptorCollection GetEvents(Attribute[] attributes)
    {
        return TypeDescriptor.GetEvents(this, attributes, true);
    }

    EventDescriptorCollection System.ComponentModel.ICustomTypeDescriptor.GetEvents()
    {
        return TypeDescriptor.GetEvents(this, true);
    }

    public TypeConverter GetConverter()
    {
        return TypeDescriptor.GetConverter(this, true);
    }

    public object GetPropertyOwner(PropertyDescriptor pd)
    {
        return _expando;
    }

    public AttributeCollection GetAttributes()
    {
        return TypeDescriptor.GetAttributes(this, true);
    }

    public object GetEditor(Type editorBaseType)
    {
        return TypeDescriptor.GetEditor(this, editorBaseType, true);
    }

    public PropertyDescriptor GetDefaultProperty()
    {
        return null;
    }

    // This is where the GetProperties() calls are
    // Ignore the Attribute for now, if it's needed support will have to be implemented
    // Should be enough for simple usage...

    PropertyDescriptorCollection ICustomTypeDescriptor.GetProperties()
    {
        return ((ICustomTypeDescriptor)this).GetProperties(new Attribute[0]);
    }

    public PropertyDescriptorCollection GetProperties(Attribute[] attributes)
    {
        // This just casts the ExpandoObject to an IDictionary<string, object> to get the keys
        return new PropertyDescriptorCollection(
            ((IDictionary<string, object>)_expando).Keys
            .Select(x => new ExpandoPropertyDescriptor(((IDictionary<string, object>)_expando), x))
            .ToArray());
    }

    // A nested PropertyDescriptor class that can get and set properties of the
    // ExpandoObject dynamically at run time
    private class ExpandoPropertyDescriptor : PropertyDescriptor
    {
        private readonly IDictionary<string, object> _expando;
        private readonly string _name;

        public ExpandoPropertyDescriptor(IDictionary<string, object> expando, string name)
            : base(name, null)
        {
            _expando = expando;
            _name = name;
        }

        public override Type PropertyType
        {
            get { return _expando[_name].GetType(); }
        }

        public override void SetValue(object component, object value)
        {
            _expando[_name] = value;
        }

        public override object GetValue(object component)
        {
            return _expando[_name];
        }

        public override bool IsReadOnly
        {
            get
            {
                // You might be able to implement some better logic here
                return false;
            }
        }

        public override Type ComponentType
        {
            get { return null; }
        }

        public override bool CanResetValue(object component)
        {
            return false;
        }

        public override void ResetValue(object component)
        {
        }

        public override bool ShouldSerializeValue(object component)
        {
            return false;
        }

        public override string Category
        {
            get { return string.Empty; }
        }

        public override string Description
        {
            get { return string.Empty; }
        }
    }
}

文章来源: Exposing properties of an ExpandoObject