You're welcome Christophe,

Glad that you've got it working.

Regards,

Steven Cheng
Microsoft Online Support

Get Secure! www.microsoft.com/security
(This posting is provided "AS IS", with no warranties, and confers no
rights.)

--------------------
| Thread-Topic: Persisting ListItemCollection values across postback, using
Vi
| thread-index: AcYiZN5a8L109yEdQx6FVz1pq34rvQ==
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| From: =?Utf-8?B?Q2hyaXN0b3BoZSBQZWlsbGV0?=
<ChristophePeillet@nospam.nospam>
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<FcSBEEOIGHA.3696@TK2MSFTNGXA02.phx.gbl>
| Subject: RE: Persisting ListItemCollection values across postback, using
Vi
| Date: Thu, 26 Jan 2006 02:40:04 -0800
| Lines: 313
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|
| I have figured out an acceptable solution by using ChildControlCreated =
| false in the ViewState properties, and then updating all the mapped
| properties in a private method, which is called every time
| CreateChildControls is fired.
|
| Thanks for the assistance on this.
|
|
|
|
|
[quoted text, click to view]
|
| > Hi Christophe,
| >
| > See you again. How are you doing on your original problems, have you
got
| > them resolved?
| > As for this problem that use ListItemCollection as custom property and
| > persist them into ViewState, I think we have to take care of the
following
| > things:
| >
| > 1. ListItemCollection class is not marked as Serializable, so they can
not
| > be directly stored in ViewState collection(can not be persisted in any
| > other persistent storage suc has file or database.......). The .net
2.0
| > ListItemCollection class implement the IStateManager interface, we can
call
| > this method to let it help us do generate the data which can be
| > persisted....
| >
| > 2. For the ListItemCollection, we can just override our custom
control's
| > LoadViewState and SaveViewState methods and manually store their state
| > value into ViewState collection...... (this is also what asp.net's
| > buildin ListControl do in their implementation)
| >
| > In addition, we have to call the TraceViewState method(in IStateManager
| > interface) when we created the ListItemCollection property's field
| > instance.... This make sure that our change on the ListItemCollection
| > instance will be persisted....
| >
| > here is a test control which demonstrate the above things:
| >
| > =====================================
| > namespace WebControlLib
| > {
| > [DefaultProperty("Text")]
| > [ToolboxData("<{0}:LinkListControl
| > runat=server></{0}:LinkListControl>")]
| > [Designer(typeof(LinkListControlDesigner),typeof(IDesigner))]
| > public class LinkListControl : WebControl, INamingContainer
| > {
| >
| > private ListItemCollection _items;
| >
| > [Bindable(true)]
| > [Category("Appearance")]
| > [DefaultValue("")]
| > [Localizable(true)]
| > public string Text
| > {
| > get
| > {
| > String s = (String)ViewState["Text"];
| > return ((s == null) ? String.Empty : s);
| > }
| >
| > set
| > {
| > ViewState["Text"] = value;
| > }
| > }
| >
| >
| > [Bindable(true)]
| > [DefaultValue((string)null)]
| > [PersistenceMode(PersistenceMode.InnerProperty)]
| >
| >
[Editor("System.Web.UI.Design.WebControls.ListItemsCollectionEditor,System.D
| > esign, Version=2.0.0.0, Culture=neutral,
PublicKeyToken=b03f5f7f11d50a3a",
| > typeof(UITypeEditor))]
| > [MergableProperty(false)]
| > [Category("Data")]
| > public ListItemCollection Items
| > {
| > get
| > {
| > if (_items == null)
| > {
| > _items = new ListItemCollection();
| >
| >
| > ((IStateManager)_items).TrackViewState();
| >
| > }
| >
| > return _items;
| > }
| > }
| >
| >
| > protected override void CreateChildControls()
| > {
| > Controls.Clear();
| >
| > LiteralControl lc = new LiteralControl("<table ><tr><td>");
| > lc.ID = "lc1";
| > Controls.Add(lc);
| >
| > if (_items == null || Items.Count == 0)
| > {
| > Label lbl = new Label();
| > lbl.ID = "lblEmpty";
| > lbl.Text = "No Link in Collection.";
| >
| > Controls.Add(lbl);
| > }
| > else
| > {
| > foreach (ListItem item in _items)
| > {
| > HyperLink link = new HyperLink();
| > link.ID = "link" + _items.IndexOf(item);
| > link.Text = item.Text;
| > link.NavigateUrl = item.Value;
| >
| > Controls.Add(link);
| > Controls.Add(new LiteralControl("<br/>"));
| > }
| > }
| >
| > lc = new LiteralControl("</td></tr></table>");
| > lc.ID = "lc2";
| > Controls.Add(lc);
| >
| > }
| >
| >
| > protected override void LoadViewState(object savedState)
| > {
| > Pair pair = (Pair)savedState;
| >
| >
| > ((IStateManager)_items).LoadViewState(pair.Second);
| >
| > base.LoadViewState(pair.First);
| > }
| >
| > protected override object SaveViewState()
| > {
| > Pair pair = new Pair();
| > pair.First = base.SaveViewState();
| > pair.Second = ((IStateManager)_items).SaveViewState();
| >
| >
| > return pair;
| > }
| >
| >
| > }
| >
| > public class LinkListControlDesigner : ControlDesigner
| > {
| > public override string GetDesignTimeHtml()

Exactly what I was looking for, you helped me out a lot. Thanks for the great example! The ViewState can be tricky sometimes.

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