DataGrid中动态添加列

     最近在项目中碰到了这样一个场景：DataGrid需要绑定到一个ObservableCollection<MyClass>，MyClass包含了一组对象，每个对象对应DataGrid的一个Column，如果把这一组对象放进MyClass的一个ObservableCollection<>属性中，则无法绑定；如果每个对象做为MyClass的一个属性，则可以动态创建Column并绑定到属性。因此我们需要能为MyClass动态添加属性，使用dynamic类型是个不错的选择。实现步骤如下：

   1、  首先定义属性

        public ObservableCollection<dynamic> DisplayPlanList {get;set;}

        并绑定到DataGrid，PlanGrid.ItemsSource = DisplayPlanList;

   2、 定义一个DynamicObject类

public class DynamicObjectClass : DynamicObject, INotifyPropertyChanged
    {
        #region DynamicObject overrides

        public DynamicObjectClass()
        {
        }

        public override bool TryGetMember(GetMemberBinder binder, out object result)
        {
            return members.TryGetValue(binder.Name, out result);
        }

        public override bool TrySetMember(SetMemberBinder binder, object value)
        {
            members[binder.Name] = value;
            OnPropertyChanged(binder.Name);
            return true;
        }

        public override IEnumerable<string> GetDynamicMemberNames()
        {
            return members.Keys;
        }

        public override bool TryGetIndex(GetIndexBinder binder, object[] indexes, out object result)
        {
            int index = (int)indexes[0];
            try
            {
                result = itemsCollection[index];
            }
            catch (ArgumentOutOfRangeException)
            {
                result = null;
                return false;
            }
            return true;
        }

        public override bool TrySetIndex(SetIndexBinder binder, object[] indexes, object value)
        {
            int index = (int)indexes[0];
            itemsCollection[index] = value;
            OnPropertyChanged(System.Windows.Data.Binding.IndexerName);
            return true;
        }

        public override bool TryDeleteMember(DeleteMemberBinder binder)
        {
            if (members.ContainsKey(binder.Name))
            {
                members.Remove(binder.Name);
                return true;
            }
            return false;
        }

        public override bool TryDeleteIndex(DeleteIndexBinder binder, object[] indexes)
        {
            int index = (int)indexes[0];
            itemsCollection.RemoveAt(index);
            return true;
        }

        #endregion DynamicObject overrides

        #region INotifyPropertyChanged

        public event PropertyChangedEventHandler PropertyChanged;

        private void OnPropertyChanged(string propertyName)
        {
            if (PropertyChanged != null)
                PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }

        #endregion INotifyPropertyChanged

        #region Public methods

        public object AddItem(object item)
        {
            itemsCollection.Add(item);
            OnPropertyChanged(Binding.IndexerName);
            return null;
        }

        #endregion Public methods

        #region Private data

        Dictionary<string, object> members = new Dictionary<string, object>();
        ObservableCollection<object> itemsCollection = new ObservableCollection<object>();

        #endregion Private data
    }


    public class SetPropertyBinder : SetMemberBinder
    {
        public SetPropertyBinder(string propertyName)
            : base(propertyName, false) { }

        public override DynamicMetaObject FallbackSetMember(DynamicMetaObject target, DynamicMetaObject value, DynamicMetaObject errorSuggestion)
        {
            return new DynamicMetaObject(
              System.Linq.Expressions.Expression.Throw(
                System.Linq.Expressions.Expression.New(
                  typeof(InvalidOperationException).GetConstructor(new Type[] { typeof(string) }),
                  new System.Linq.Expressions.Expression[] { System.Linq.Expressions.Expression.Constant("Error") }),
              this.ReturnType), BindingRestrictions.Empty);
        }
    }

    public class GetPropertyBinder : GetMemberBinder
    {
        public GetPropertyBinder(string propertyName)
            : base(propertyName, false) { }

        public override DynamicMetaObject FallbackGetMember(DynamicMetaObject target, DynamicMetaObject value)
        {
            return new DynamicMetaObject(
              System.Linq.Expressions.Expression.Throw(
                System.Linq.Expressions.Expression.New(
                  typeof(InvalidOperationException).GetConstructor(new Type[] { typeof(string) }),
                  new System.Linq.Expressions.Expression[] { System.Linq.Expressions.Expression.Constant("Error") }),
              this.ReturnType), BindingRestrictions.Empty);
        }
    }

该类继承自DynamicObject，主要提供了设置属性、获取属性功能。

3、 为DataGrid动态添加列

dynamic item = new DynamicObjectClass();
item.ID = Guid.NewGuid();
item.Name = "名称#";
ObjectList.Add(item);
PlanGrid.Columns.Add(new DataGridTextColumn() { Header = "编号", Binding = new Binding("ID") });
PlanGrid.Columns.Add(new DataGridTextColumn() { Header = "名称", Binding = new Binding("Name") });

上面代码中的ID、Name是硬编码设置的属性，也可以根据参数动态设置属性，如下：

foreach (DynamicObjectClass obj in ObjectList)
{
    obj.TrySetMember(new SetPropertyBinder(propName), bindingData);
}

上面代码的意思是为每个DynamicObject添加一个名为propName的属性，并绑定到bindingData对象。其中每个DynamicObject对应DataGrid的一行，propName对应DataGrid

的一列，可按如下方式为DataGrid添加一列：

DataGridTextColumn column = new DataGridTextColumn();

string propName = "New Column";

column.Binding = new Binding(propName);

PlanGrid.Columns.Add(column);

如果需要可通过以下方式获取某个属性对应的绑定值：

object ID;
obj.TryGetMember(new GetPropertyBinder("ID"), out ID);

以上实现方式参考了网上若干资料，具体网址没有保存下来，无法提供链接，希望原作者见谅！