• 0

[ASP.Net] Repeaters with Dynamic ItemTemplates


Question

Hey guys, I have abit of a pickle. I want to have in an ItemTemplate a couple of Templates and only want to show one based on the data for that row. Basically I have a normal product list, and then people want to be able to put headings in randomly into that list, so I have a seperate bit of html for that. I thought I might be able to set the table row's to runat="server" and simply hide the ones that I don't need, but I have a code block inside of that row which apparently .Net does not approve of when its parent is set to runat="server" :s. I'm not sure if this would work anyway since the columns are going to be different for a Product row and a heading row, so ASP is still going to try and put info into the bit that I'm going to set to visible="false", which will obviously die with errors?

So I spose the question is, is there a way to use if statements with DataBinded ..data?

Just incase the above doesn't make much sense, here is roughly what I want to do, :p

<ItemTemplate>
   <% if(Data["IsNormalRow"] == true) { %>
   <tr>
	   <td>My Product List</td>
	</tr>
   <% } else if(Data["IsHeadingRow"] == true) { %>
	<tr>
	   <td><h1>My Heading</h1></td>
	</tr>
	<% } else if (Data["IsSomeOtherType"] == true) { %>
	<tr>
	   <td>Another type here</td>
	</tr>
   <% } %>
</ItemTemplate>

Is there a way? :pinch:

11 answers to this question

Recommended Posts

  • 0

Well, instead of trying to force logic into the markup page, what you could do is subclass the standard repeater control, to provide your own item header implementation:

namespace MyCustomControls
{
	public class MyExtendedRepeater : Repeater
	{
		private ITemplate itemHeaderTemplate;

		[TemplateContainer(typeof(ItemHeaderContainer)), PersistenceMode(PersistenceMode.InnerProperty)]
		public ITemplate ItemHeaderTemplate
		{
			get { return itemHeaderTemplate; }
			set { itemHeaderTemplate = value; }
		}

		protected override void OnItemCreated(RepeaterItemEventArgs e)
		{
			base.OnItemCreated(e);

			if (!e.Item.DataItem == null && (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem))
			{
				if (<insert your header logic here>)
				{
					ItemHeaderContainer container = new ItemHeaderContainer();
					ItemHeaderTemplate.InstantiateIn(container);

					container.DataItem = e.Item.DataItem;
					container.DataBind();
				}
			}
		}
	}

	public class ItemHeaderContainer : Control, INamingContainer
	{
		private object dataItem;
		public virtual object DataItem
		{
			get { return dataItem; }
			set { dataItem = value; }
		}
	}
}

What the above does, is extends the standard .NET implementation of the Repeater, but supplements it with an additional property called ItemHeaderTemplate, which you can use to express your individual headers. What you would need to do is specifically state the logic to decide whether or not the header is needed. I didn't spend to long on this, but of course from here you can expand it to make any generic Grouping Repeater.

Use it in code as follows:

<%@ Register Assembly="App_Code" Namespace="MyCustomControls" TagPrefix="custom" %>

^ That is on the assumption that you've got this class in your App_Code.

<custom:MyExtendedRepeater ID="repeat_Data" runat="server">
	 <ItemHeaderTemplate>item header here</ItemHeaderTemplate>
	 <ItemTemplate>data here</ItemTemplate>
</custom:MyExtendedRepeater>

Is that any help?

  • 0

Hey Antaris. Cheers for the answer. I have the following,

protected override void OnItemCreated(RepeaterItemEventArgs e)
		{
			base.OnItemCreated(e);

			if (e.Item.DataItem != null && (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem))
			{
				DataRowView dt = (DataRowView)e.Item.DataItem;
				if (dt.DataView.Table.Columns["IsHeading"] != null)
				{
					if ((dt["IsHeading"].ToString()) == "true")
					{
						ItemHeaderContainer container = new ItemHeaderContainer();
						ItemHeaderTemplate.InstantiateIn(container);

						container.DataItem = e.Item.DataItem;
						container.DataBind();
					}
				}
			}
		}

Am I supposed to do something after container.DataBind()? I was stepping through the code, and after that line, it starts trying to put the data into an ItemTemplate.. not an ItemTemplateHeader. :s

  • 0

Bah, sif not let me edit. Sorry, it does go into the ItemHeaderTemplate, but then keeps on moving down into ItemTemplate, and perhaps the ItemTemplate overwrites the ItemHeaderTemplate so it never appears.

Edit Edit: Ok, first problem sovled.

base.Controls.Add(container);

Adds my ItemHeaderTemplate.. now the problem is that it still tries to add an empty item... it seems to do it after the OnItemCreated.. so I can't simply delete the empty item. :(

Edited by Pc_Madness
  • 0

The implementation I tested:

namespace Test
{
	public class MyRepeater : Repeater
	{
		[TemplateContainer(typeof(ItemHeaderContainer)), PersistenceMode(PersistenceMode.InnerProperty)]
		public ITemplate ItemHeaderTemplate { get; set; }

		protected override void OnItemCreated(RepeaterItemEventArgs e)
		{
			base.OnItemCreated(e);

			if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem)
			{
				TestItem testItem = e.Item.DataItem as TestItem;
				if (testItem.Header)
				{
					ItemHeaderContainer container = new ItemHeaderContainer();
					ItemHeaderTemplate.InstantiateIn(container);

					container.DataItem = testItem;
					container.DataBind();
					this.Controls.Add(container);
				}
			}
		}
	}

	public class TestItem
	{
		public string Name { get; set; }
		public bool Header { get; set; }
	}

	public class ItemHeaderContainer : Control, INamingContainer
	{
		public object DataItem { get; set; }
	}
}

Doesn't create empty entries, it just works :s

<%@ Page Language="C#" AutoEventWireup="true"  CodeFile="Default.aspx.cs" Inherits="_Default" %>
<%@ Register TagPrefix="local" Assembly="App_Code" Namespace="Test" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">t;html xmlns="http://www.w3.org/1999/xhtml">;head runat="server">
	<title>Untitled Page</title>
</head>
<body>
	<form id="form1" runat="server">
	<div>
		<local:MyRepeater ID="repeat_Test" runat="server">
			<ItemTemplate>Here is a test item</ItemTemplate>
			<ItemHeaderTemplate><h3>Here is a header</h3></ItemHeaderTemplate>
		</local:MyRepeater>
	</div>
	</form>
</body>
</html>

  • 0
  Antaris said:
The implementation I tested:

How are your rows done in your DataTable? I have rows filled with Product information, and then randomy there are blank rows which has IsHeading and Title filled in and nothing else. Are you sure you aren't combing the two rows into together? (Perhaps I didn't explain it properly :()

I don't understand how your way could work though, at the end of OnItemCreated e (an ItemTemplate) gets added to the Repeater automatically, as I understand it? But we chuck in our own Item before hand, so both are using the same DataRow, and since the DataItem is basically empty, the ItemTemplate code errors.

There doesn't seem to be a way to remove 'e'... is there a way to control what Item gets passed to OnItemCreated instead? Time to venture into the scary world of MSDN :(

  • 0
  Pc_Madness said:
How are your rows done in your DataTable? I have rows filled with Product information, and then randomy there are blank rows which has IsHeading and Title filled in and nothing else. Are you sure you aren't combing the two rows into together? (Perhaps I didn't explain it properly :()

Well, that could be your problem. The binding process will bind every row as an Item (or AlternatingItem). So if you randomly have rows that have no data, just header information, then it will create your ItemHeader, and then create your Item (its not smart enough to realise you don't want to do that.). You may have to have a standard row with an additional column for heading, instead of seperating them out.

The class I have, 'TestItem' defines a property called Header. This would be the equivalent to a header column in your datatable, for all rows.

  • 0
  Antaris said:
Well, that could be your problem. The binding process will bind every row as an Item (or AlternatingItem). So if you randomly have rows that have no data, just header information, then it will create your ItemHeader, and then create your Item (its not smart enough to realise you don't want to do that.). You may have to have a standard row with an additional column for heading, instead of seperating them out.

Yeah, I was hoping to avoid that since the headings don't relate to a single row obviously. The other option I spose is to move the few bits of code I have in ItemTemplate into the Code behind and chuck in some error handling to ignore it if its a heading row, and then set that rows visibility to false. :)

Thanks for your help. :)

  • 0

*bump* Only just spotted this now. I have a Repeater which is supposed to be displaying 141 rows of Products, and then it also has 3 heading rows. So on page load I have 144 items, but on Post back I only have 141, so it trims 3 off the end of the array (which is quite bad obviously :p). If I don't do a redirect after the postback, my heading rows are appearing as normal rows again. Do I have to do something so that they survive a postback? :(

  • 0
  Pc_Madness said:
Nope. :s

Meh, no matter, I just went back to using a normal repeater and passing the data to the code behind and toggle a row on and off. Its kinda pointless to use a custom repeater if I can't control what kind of item the Repeater will be making.

This topic is now closed to further replies.
  • Recently Browsing   0 members

    • No registered users viewing this page.
  • Posts

    • You can do that right now, so what stops you? Nobody forbids you from installing Windows 10 on your PC.
    • Users: "Bring back the adjustable Taskbar!" Microsoft: "Here's an adjustable Volume Indicator!"
    • The flyouts appear in the top left in Windows 8 as well.
    • Supposed Samsung Galaxy Z Fold7 gets unpacked before July in a video by Sagar Naresh Bhavsar We are just a few days away from the official launch of Samsung's premium foldables: the Galaxy Z Fold7 and Galaxy Z Flip7. The second Unpacked event is expected to take place in New York, marking Samsung's return to the city after two years. Samsung has already shared two teasers with the Galaxy Z Fold7 in focus, suggesting that this year's Galaxy Z Fold7 will be taller and wider compared to last year's Galaxy Z Fold6. The teaser also highlights the thinness of the upcoming Z Fold7, claiming that it will be the thinnest and lightest foldable from Samsung ever. Samsung's claims appear to be true, as, way ahead of its official unveiling, a Korean YouTuber, TheSINZA, has shared a video comparing the supposed Galaxy Z Fold7 with the standard Galaxy Z Fold6 and the Galaxy Z Fold6 Special Edition, which launched in China and Korea. The dummy unit of the Galaxy Z Fold7, when compared with last year's foldables, reveals just how thin and lightweight the upcoming foldable could be. The video suggests that the Z Fold7 will weigh 215 grams, much lighter than the Galaxy Z Fold6 Special Edition, which weighed 236 grams. image by TheSINZA via YouTube When the Galaxy Z Fold7 dummy unit is put side-by-side against the Z Fold6 Special Edition, it appears to be noticeably thinner, measuring 9mm compared to the 10.6 mm thickness of the Galaxy Z Fold6 SE. From the front, the Galaxy Z Fold7 looks similar to the Galaxy Z Fold6 Special Edition, but different than the Galaxy Z Fold6. image by TheSINZA via YouTube Though the volume rockers and power buttons appear thin in the Galaxy Z Fold7 dummy unit, they are located in the same place as previous foldables. The dummy unit is also compared with the Galaxy S25 Ultra, and in terms of thickness, it is almost identical. This would mean that the foldable won't feel different compared to Samsung's premium slab phone. Samsung could unveil its foldables on July 9. There are also rumors that an affordable Galaxy Z Flip7 FE could also debut during the event.
    • Thought so, then why would they replace the S+ series with this
  • Recent Achievements

    • First Post
      emptyother earned a badge
      First Post
    • Week One Done
      Crunchy6 earned a badge
      Week One Done
    • One Month Later
      KynanSEIT earned a badge
      One Month Later
    • One Month Later
      gowtham07 earned a badge
      One Month Later
    • Collaborator
      lethalman went up a rank
      Collaborator
  • Popular Contributors

    1. 1
      +primortal
      660
    2. 2
      ATLien_0
      270
    3. 3
      Michael Scrip
      218
    4. 4
      Steven P.
      161
    5. 5
      +FloatingFatMan
      157
  • Tell a friend

    Love Neowin? Tell a friend!