TRULY Understanding Dynamic Controls (Part 2)

Dynamically adding user controls, and then setting custom properties on those instances? | keyongtech

Thu, 22 Jan 2009 08:27:20 GMT

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re: TRULY Understanding Dynamic Controls (Part 2)

Stephan — Mon, 01 Sep 2008 18:17:32 GMT

Hi, hope you still monitor the part, but I'm totally lost here, and that is also because I don't understand all of it complety.

In my case I made a small example which in total uses 4 nested UC's and each UC has a textbox, button and checkbox. The UC's are in a ItemTemplate of the repeater which is nested. Now on every level I the button adds a new control to the list using:

protected void Button2_Click(object sender, EventArgs e)

{

ArrayList list = new ArrayList();

int index = 0;

foreach (RepeaterItem rptItem in rptFirst.Items)

{

WebUserControl2 WebUserControl = rptItem.FindControl("Item") as WebUserControl2;

if (WebUserControl != null)

{

WebUserControl2 ctrl = WebUserControl as WebUserControl2;

list.Add(ctrl);

index++;

}

index++;

WebUserControl2 _ctrl = LoadControl("WebUserControl2.ascx") as WebUserControl2;

_ctrl.myText = "NEW ITEM";

list.Add(_ctrl);

Repeater1.DataSource = list;

Repeater1.DataBind();

}

Basically every uc has a procedure like this. Then when I also have, on every UC the following procedure:

protected void Repeater1_ItemCreated(object sender, RepeaterItemEventArgs e)

{

if (!e.Item.ItemType.Equals(ListItemType.Separator))

{

//Postback then e.item.DataItem is null

if (e.Item.DataItem != null)

{

WebUserControl2 WebUserControl = e.Item.FindControl("Item") as WebUserControl2;

WebUserControl.myText = ((WebUserControl2)e.Item.DataItem).myText;

WebUserControl.myCheckBox = ((WebUserControl2)e.Item.DataItem).myCheckBox;

}

As you can see I actually bind a (Arry)list of UC to the repeater.

I want to setup this small example without binding to a Db, that is why I use the ArrayList.

No When I add a control it appears fine. On this control I can add 1..N Child UC and on the child control I can add 1..N UC (three levels deep). This all works fine, untill I press Add usercontrol button on the highest level. Then I still have the first UC I added and also the second new UC, but all the Child controls ( and their child controls) of the first added control are gone.

All the controls have the procedures I have included above.

How can I maintain the state of the child controls which are already there when I add a control on the highest level.

I was told the problem is I recreate the controls in ItemCreated event, so it is actually a new control which, of course has no childcontrols. If that is true, what would be the solution for this?

TIA Stephan

re: TRULY Understanding Dynamic Controls (Part 2)

InfinitiesLoop — Wed, 16 Apr 2008 23:56:43 GMT

Pablo -- have you tried setting the custom templates on the repeater from Init instead of Load? It doesnt appear there's any reason to delay it. Not sure if thats the problem but I'd do that anyway. Also, I'd hook the databinding event before adding the panel to the control collection. I dont think it matters in this case but as a practice I try to do everything I can to the control before adding it, unless there's a good reason to do it afterward. Let me know if either of those helps...

re: TRULY Understanding Dynamic Controls (Part 2)

Pablo — Wed, 16 Apr 2008 22:08:22 GMT

Question about ItemCommand firing...

I have a repeater on a page which fires the ItemCommand and OnItemDatabound events as expected. My problem happens when I ripped out the contents of <ItemTemplate> on the page's repeater and put the contents into a class method InstantiateIn which inherits ITemplate. The problem I'm having is that the ItemCommand won't fire anymore. My handler is still wired to the page in the Page_Init.

Do you know what I could be doing wrong?

code sample below:

page markup

==========

<asp:Repeater ID="rptFoo" runat="server">

</asp:Repeater>

page code behind

===============

protected void Page_Init(object sender, EventArgs e)

{

rptFoo.ItemCommand += new RepeaterCommandEventHandler(rptFoo_ItemCommand);

}

protected void Page_Load(object sender, EventArgs e)

{

CustomItemTemplate citItem = new CustomItemTemplate(ListItemType.Item);

CustomItemTemplate citAlternating = new CustomItemTemplate(ListItemType.AlternatingItem);

rptFoo.ItemTemplate = citItem;

rptFoo.AlternatingItemTemplate = citAlternating;

if (!Page.IsPostBack)

{

BindData();

}

protected void rptFoo_ItemCommand(object source, RepeaterCommandEventArgs e)

{

// won't fire when implementing my class file.

}

CustomItemTemplate.cs

===================

public class CustomItemTemplate : ITemplate

{

Panel pan;

public ListItemType ItemType;

public CustomItemTemplate(ListItemType itemType)

{

this.ItemType = itemType;

}

void ITemplate.InstantiateIn(Control container)

{

pan = new Panel();

// if the parent control is a WebControl...

if ((container) is WebControl)

{

// get a strongly-typed reference to the containing item

WebControl webCtl = (WebControl)container;

// set the panel's size so that it fully cover's its containers

pan.Width = webCtl.Width;

pan.Height = webCtl.Height;

}

switch (this.ItemType)

{

case ListItemType.Item:

pan.Controls.Add(new LiteralControl("<tr align=\"left\" class=\"item\">"));

break;

case ListItemType.AlternatingItem:

pan.Controls.Add(new LiteralControl("<tr align=\"left\" class=\"alternatingItem\">"));

break;

}

pan.Controls.Add(new LiteralControl("<td>"));

pan.Controls.Add(new HiddenField());

pan.Controls.Add(new CheckBox());

pan.Controls.Add(new LiteralControl("</td><td width=\"325\">"));

pan.Controls.Add(new LinkButton());

pan.Controls.Add(new LiteralControl("<br />"));

pan.Controls.Add(new Label());

pan.Controls.Add(new LiteralControl("</td></tr>"));

container.Controls.Add(pan);

pan.DataBinding += new EventHandler(pan_DataBinding);

}

private void pan_DataBinding(object sender, System.EventArgs e)

{

fooProduct p;

if ((pan.NamingContainer) is RepeaterItem)

{

p = (fooProduct)(((RepeaterItem)pan.NamingContainer).DataItem);

}

else

{

return;

}

((LinkButton)pan.Controls[5]).ID = "linkBtnFoo";

((LinkButton)pan.Controls[5]).Text = p.FooName);

((LinkButton)pan.Controls[5]).CommandName = "Go";

((LinkButton)pan.Controls[5]).CommandArgument = p.fooId;

}

TIA, Pablo

re: TRULY Understanding Dynamic Controls (Part 2)

InfinitiesLoop — Thu, 06 Dec 2007 07:09:23 GMT

Divya -- sure, you could either manually build up the html in the code behind with a foreach or you can embed that foreach directly into the page using the old asp style <% %> code blocks.

You might also be interested in the ASP.NET MVC framework currently under development.

weblogs.asp.net/.../asp-net-mvc-framework-part-1.aspx

re: TRULY Understanding Dynamic Controls (Part 2)

Divya — Thu, 06 Dec 2007 05:56:08 GMT

can we display data without using databound controls using datatable.

re: TRULY Understanding Dynamic Controls (Part 2)

InfinitiesLoop — Tue, 09 Oct 2007 17:06:31 GMT

Ashok -- maybe this will help you.

msdn2.microsoft.com/.../w70c655a.aspx

or perhaps this

www.codeproject.com/.../aspnetusercontrol2.asp

re: TRULY Understanding Dynamic Controls (Part 2)

Ashok Kumar — Tue, 09 Oct 2007 06:15:29 GMT

thanks man,

But Can you suggest me how can I typecast loaded control to the loaded control class from Control class to set the properties of this control. And I will be getting this control classname at runtime only.

Regards,

AKS.

http://www.aksClassifieds.com

forums.aksclassifieds.com

youtube.aksclassifieds.com

re: TRULY Understanding Dynamic Controls (Part 2)

Josevader — Sat, 22 Sep 2007 22:59:38 GMT

This article is truly a great asset. I've searched all over for information that is sound, succinct, and easy to understand. You have achieved all this. Thanks for the enlightenment.

re: TRULY Understanding Dynamic Controls (Part 2)

InfinitiesLoop — Thu, 13 Sep 2007 18:54:59 GMT

nyimalay -- You'll have to provide me some code so I can understand what is wrong. Sounds like you probably have a significant amount of code with database lookups and all that. Try to narrow it down as compact as possible while still reproducing the problem.