Introduction
I've never really been much of a web-developer and never thought I'd find web-development all that interesting. But I must say I've been quite fascinated by what little ASP.NET I've done up till now, which is not a lot to be honest. One control I found particularly useful was the Repeater
control, but I struggled a little when I tried to implement nested repeaters using an XML file as the data store. Eventually, the solution turned out to be embarrassingly easy, and I thought I'd write a little article for other first-timers who might encounter the same annoying situation I did.
Note to readers
I assume that you already know how to use a Repeater
control. This article only shows you how to implement nested repeaters and will not attempt to explain repeaters in general.
Example
I am going to demonstrate a simple ASP.NET web application that will list out a Cricket World XI using an XML file as the input-data. Eventually, modification of the team simply involves a change in the XML file with no changes required either in the aspx pages or in the code-behind files.
My XML file
Essentially I have four categories - and each category has one or more players.
Implementing nested repeaters
I am going to list the categories first and inside each category I will list the players under that category. Lets first add the outter repeater that will list the categories.
We now add the inner repeater to the <ItemTemplate>
tag of the outter repeater.
Writing the code-behind code
Alright, I know that "code-behind code" sounds weird, but I couldn't think of anything better sounding and if anyone has any better ideas, please drop me a line. Anyway we setup the first repeater in the Page_Load
event handler as usual.
private void Page_Load(object sender, System.EventArgs e)
{
DataSet ds = new DataSet();
ds.ReadXml(MapPath("./XMLFile1.xml"));
CategoryRepeater.DataSource = ds;
CategoryRepeater.DataBind();
}
For setting up the outter repeater, we handle the ItemDataBound
event of the Repeater
class which is raised when an item is data-bound but before it is rendered on the page. We now get a reference to the PlayerRepeater
control using RepeaterItem.FindControl
and set its data source using CreateChildView
and the automatic relation that's made for us - category_cricketer
. By the way I was quite impressed by that, I never expected automatic relations to be created based on the XML. Pretty cool I think!
private void CategoryRepeater_ItemDataBound(object sender,
System.Web.UI.WebControls.RepeaterItemEventArgs e)
{
RepeaterItem item = e.Item;
if( (item.ItemType == ListItemType.Item) ||
(item.ItemType == ListItemType.AlternatingItem) )
{
PlayerRepeater = (Repeater) item.FindControl("PlayerRepeater");
DataRowView drv = (DataRowView)item.DataItem;
PlayerRepeater.DataSource = drv.CreateChildView("category_cricketer");
PlayerRepeater.DataBind();
}
}
That's all.
The output
I got the below output when I viewed the web-form in my browser.
Conclusion
Feedback and criticism is welcome as usual. I'd also like to thank Aravind Corera (Chennai based C# MVP) who gave me the right URLs to solve this problem when I was tearing my hair out in frustration.
Nish Nishant is a technology enthusiast from Columbus, Ohio. He has over 20 years of software industry experience in various roles including Chief Technology Officer, Senior Solution Architect, Lead Software Architect, Principal Software Engineer, and Engineering/Architecture Team Leader. Nish is a 14-time recipient of the Microsoft Visual C++ MVP Award.
Nish authored C++/CLI in Action for Manning Publications in 2005, and co-authored Extending MFC Applications with the .NET Framework for Addison Wesley in 2003. In addition, he has over 140 published technology articles on CodeProject.com and another 250+ blog articles on his WordPress blog. Nish is experienced in technology leadership, solution architecture, software architecture, cloud development (AWS and Azure), REST services, software engineering best practices, CI/CD, mentoring, and directing all stages of software development.
Nish's Technology Blog :
voidnish.wordpress.com