Reputation: 3238
Here is my custom control code:
namespace MyControlNameSpace
{
public class MyControlItemCommandEventArgs : CommandEventArgs
{
private MyControlItem _item;
private object _commandSource;
public MyControlItemCommandEventArgs(MyControlItem item, object commandSource, CommandEventArgs cea) : base(cea)
{
_item = item;
_commandSource = commandSource;
}
public MyControlItem Item { get{ return _item; } }
public object CommandSource { get{ return _commandSource; } }
}
public class MyControlItem : Control, IDataItemContainer
{
public MyControlItem(object dataItem, int index)
{
_dataItem = dataItem;
_dataItemIndex = _displayIndex = index;
}
private readonly object _dataItem;
private readonly int _dataItemIndex;
private readonly int _displayIndex;
public object DataItem { get { return _dataItem; } }
public int DataItemIndex { get { return _dataItemIndex; } }
public int DisplayIndex { get { return _displayIndex; } }
protected override bool OnBubbleEvent(object source, EventArgs args)
{
if (args is CommandEventArgs)
{
var e = new MyControlItemCommandEventArgs(this, source, (CommandEventArgs)args);
base.RaiseBubbleEvent(this, e);
return true;
}
return false;
}
}
public delegate void ItemEventHandler(object sender, MyControlItemCommandEventArgs e);
[DefaultProperty("Text")]
[ToolboxData("<{0}:MyControl runat=server></{0}:MyControl>")]
public class MyControl : CompositeDataBoundControl, IPrivilage
{
public event ItemEventHandler ItemCommand;
protected virtual void OnItemCommand(MyControlItemCommandEventArgs e)
{
if (ItemCommand != null)
ItemCommand(this, e);
}
protected override bool OnBubbleEvent(object source, EventArgs args)
{
// only bother bubbling appropriate events
if (args is MyControlItemCommandEventArgs)
{
OnItemCommand((MyControlItemCommandEventArgs)args);
return true;
}
return false;
}
protected override int CreateChildControls(IEnumerable dataSource, bool dataBinding)
{
// here I'm adding some controls like buttons and other
// Iterate for ItemTemplate
foreach (object dataItem in dataSource)
{
if (ItemTemplate != null)
{
// create instance of MyControlItem control
var item = new MyControlItem(dataItem, count++);
// instantiate in new item object
ItemTemplate.InstantiateIn(item);
// add item to Controls collection
Controls.Add(item);
// need to support <%# %> expressions
item.DataBind();
}
}
// some code here
}
}
In .aspx page:
protected void Page_Load(object sender, EventArgs e)
{
// if it's not post back then get the data and assign to MyControl DataSource property
if(!IsPostBack)
GetData();
}
protected void MyControl1_OnItemCommand(object sender, MyControlItemCommandEventArgs e)
{
var x = e.DataItem;
// x here is always null;
}
As you can see I can't get e.DataItem when OnItemCommand event because it's always null.
I tried to remove if(!IsPostBack)
in Page_Load
so that every time page load datasource assigned, but this is not right, I should be able to not assigning datasource if it's PostBack
like in Asp.Net Repeater
control.
Any Idea how to do it?
Upvotes: 0
Views: 829
Reputation: 31248
The OnItemCommand
event is raised on post-back. At that point, if the CompositeDataBoundControl
has ViewState
enabled, it will recreate the child controls without querying the database. Your CreateChildControls
method will be called with dataBinding
set to false
, and the dataSource
will be an enumerable sequence of null
objects which serve as placeholders for the actual data.
You'll get the same behaviour in any data-bound control. If you try the same thing with a Repeater
, you'll see that the e.Item.DataItem
is null
in the ItemCommand
event.
Upvotes: 0