asp.net CompositeDataBoundControl for a single object

Question

I have created a CompositeDataBoundControl that i can databind perfectly well. Now i want to do the same thing, but not for a list of objects, but for a single object. Reasons is that i want my colleagues to have the ability to simply use the <%# Eval("X") %> in their front end code.

The problem is that the CompositeDataBoundControl has a method that i have to override, which only accepts a collection as a datasource

CreateChildControls(System.Collections.IEnumerable dataSource, bool dataBinding)

Is there a way to do the same thing for a single object?

Answer 1

You need to override the DataSource property

public class SingleObjectView : CompositeDataBoundControl
    {
        private object dataSource;
        public override object DataSource
        {
            get { return new List<object> { dataSource }; }
            set { dataSource = value; }
        }


        protected override int CreateChildControls(System.Collections.IEnumerable dataSource, bool dataBinding)
        {
            SingleItem singleItem = null;
            if (dataBinding)
            {
                var it = dataSource.GetEnumerator();
                it.MoveNext();

                singleItem = new SingleItem(it.Current);
            }
            else
            {
                singleItem = new SingleItem(null);
            }

            ItemTemplate.InstantiateIn(singleItem);
            Controls.Add(singleItem);
            if (dataBinding)
                singleItem.DataBind();
            return 1;
        }


        [PersistenceMode(PersistenceMode.InnerProperty), TemplateContainer(typeof(SingleItem))]
        public ITemplate ItemTemplate { get; set; }
    }

    public class SingleItem : Control, IDataItemContainer
    {
        public SingleItem(object dataItem)
        {
            DataItem = dataItem;
        }
        public object DataItem { get; set; }

        public int DataItemIndex
        {
            get { return 0; }
        }

        public int DisplayIndex
        {
            get { return 0; }
        }
    }

edit to show the usage

<ctrl:SingleObjectView ID="productView" runat="server">
   <ItemTemplate>
        <%# Eval("ProductName") %>
        <br />
        <%# Eval("Price","{0:c}") %>
   </ItemTemplate>
</ctrl:SingleObjectView>

 protected void Page_Load(object sender, EventArgs e)
 {
    if (!Page.IsPostBack)
      {
        productView.DataSource = new { ProductName="My Product", Price="10"};
        productView.DataBind();
      }
 }

So the DataSource receives an object which doesn't implement IEnumerable, but overriding the DataSource property of the SingleObjectView control, ensures that CreateChildControls is called.

Answer 2

What about create a list of control, add one single object and then call the method?