Binding DynamicObject to a DataGrid with automatic column generation?

c#-4.0, data-binding, datagrid, dynamicobject, wpf

Solution

There is no uniform way to query dynamic properties, generally it's expected that you know them ahead of time. With `DynamicObject`, implementers may override `GetMemberNames` and that generally gives you the properties, however it is really meant for debugging because there is no requirement that it provide all properties. Otherwise if it's your own `DynamicObject` you just have to write your own method to get the properties based on your dynamic implementation. For example `ExpandoObject` lets you query all the properties using the `IDictionary` interface.

So once you have a way to get your properties you need to tell the DataGrid. Unfortunately with a DataGrid, the issue with implementing `ICustomTypeDescriptor` to tell the DataGrid about your properties is that DataGrid gets the TypeDescriptors using the Type not the instance, which is a problem for Dynamic objects, however implementing `ITypedList` on the collection of DynamicObjects will work with the very tiny gotcha of if you don't implement the non-generic `IList` interface on your collection, it will be stripped out before it gets to the point where it checks for `ITypeList`.

So in summary, Implement a Collection with `ITypedList` and `IList`. With `ITypedList` return null for `GetListName` and just implement `GetItemProperties(PropertyDescriptor[] listAccessors)`; Ignore `listAccessors` and return a PropertyDescriptorCollection of PropertyDescriptors for each member named based on the best represented Dynamic object instance in your list (most likely just the first object). You do have to implement a subclass of PropertyDescriptor, an easy and general way to the Get/Set value is to use the opensource framework Dynamitey

using System;
using System.ComponentModel;
using Dynamitey;
public class DynamicPropertyDescriptor:PropertyDescriptor
{
        public DynamicPropertyDescriptor(string name) : base(name, null)
        {
        }

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

        public override object GetValue(object component)
        {
           return Dynamic.InvokeGet(component, Name);
        }

        public override void ResetValue(object component)
        {

        }

        public override void SetValue(object component, object value)
        {
            Dynamic.InvokeSet(component, Name, value);
        }

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

        public override Type ComponentType
        {
            get { return typeof(object); }
        }

        public override bool IsReadOnly
        {
            get { return false; }
        }

        public override Type PropertyType
        {
            get
            {
                return typeof (object);
            }
        }
}

Problem

Original source