Nested DataList in ASP.NET

Rohatash Kumar
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This article shows how to implement a nested DataList and also display category and subcategory using a nested DataList. You create two tables, one for category and another for subcategory and also create a stored procedure for selecting category and sub category from both tables in SQL Server. You have to create a web site and add a new page to the website. Drag and drop two DataList controls on the form, one is to bind category and the other is for subcategory. Let's take a look at a practical example. We create tables for category and subcategory.

Creating Table in SQL Server Database

Now create two tables named MajorCategory and MinorCategory. We create CategoryID in MajorCategory table that is the foreign key for the MinorCategory also set the identity property of the CategoryID. The table looks as below.

MajorCategory Table

MinorCategory Table

Creating a Stored Procedure

Now create a stored procedure to select data from both tables.

ALTER PROCEDURE [dbo].[usp_GetProductsForCategories]

SELECT * FROM MajorCategory WHERE CategoryID IN

( SELECT CategoryID FROM MinorCategory )

SELECT p.MinorCategoryId , p.SubCategoryName ,p.CategoryID FROM MinorCategory p

First you have to create a web site.

Go to Visual Studio 2010
New-> Select a website application
Click OK

Now add a new page to the website.

Go to the Solution Explorer
Right Click on the Project name
Select add new item
Add new web page and give it a name
Click OK

Now create a new website and drag and drop two DataList controls onto the aspx page. The DataList code looks like this.

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="categorySubcategory.aspx.cs"

Inherits="categorySubcategory" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

</head>

<body>

<div>

<ul>

<asp:DataList ID="outerDataList" runat="server" OnItemDataBound="outerRep_ItemDataBound">

<li>

<asp:Label Font-Size="Large" Font-Bold="true" ID="lblCategoryName" runat="server"

Text='<%# Eval("CategoryName") %>' />

</li>

<ul>

<asp:DataList ID="innerDataList" runat="server">

<asp:HyperLink ID="hlProductName" runat="server" Text='<%# Eval("SubCategoryName")%>' />

</li>

</ItemTemplate>

</asp:DataList>

</ul>

</ItemTemplate>

</asp:DataList>

</ul>

</div>

</form>

</body>

</html>

Now add the following namespaces.

using System.Data.SqlClient;

using System.Data;

Now write the connection string to connect to the database.

string strConnection = "Data Source=.; uid=sa; pwd=wintellect;database=registration;";

Now double-click on the page and write the following code for binding the data with the DataList.

private void BindData()

{

SqlConnection myConnection = new SqlConnection("Data Source=.; uid=sa; pwd=wintellect;database=registration;");

SqlCommand myCommand = new SqlCommand("usp_GetProductsForCategories", myConnection);

myCommand.CommandType = CommandType.StoredProcedure;

SqlDataAdapter ad = new SqlDataAdapter(myCommand);

DataSet ds = new DataSet();

ad.Fill(ds);

// Attach the relationship to the dataSet

ds.Relations.Add(new DataRelation("CategoriesRelation", ds.Tables[0].Columns["CategoryID"],

ds.Tables[1].Columns["CategoryID"]));

outerDataList.DataSource = ds.Tables[0];

outerDataList.DataBind();

}

Now write the below code on the OnItemDataBound event of the DataList.

protected void outerRep_ItemDataBound(object sender, DataListItemEventArgs e)

{

if (e.Item.ItemType == ListItemType.Item)

{

DataRowView drv = e.Item.DataItem as DataRowView;

DataList innerDataList = e.Item.FindControl("innerDataList") as DataList;

innerDataList.DataSource = drv.CreateChildView("CategoriesRelation");

innerDataList.DataBind();

}

In Codebehind write the following code like this.

Codebehind

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.Data;

using System.Data.SqlClient;

public partial class categorySubcategory : System.Web.UI.Page

{

protected void Page_Load(object sender, EventArgs e)

{

BindData();

}

private void BindData()

{

SqlConnection myConnection = new SqlConnection("Data Source=.; uid=sa; pwd=wintellect;database=registration;");

SqlCommand myCommand = new SqlCommand("usp_GetProductsForCategories", myConnection);

myCommand.CommandType = CommandType.StoredProcedure;

SqlDataAdapter ad = new SqlDataAdapter(myCommand);

DataSet ds = new DataSet();

ad.Fill(ds);

// Attach the relationship to the dataSet

ds.Relations.Add(new DataRelation("CategoriesRelation", ds.Tables[0].Columns["CategoryID"],

ds.Tables[1].Columns["CategoryID"]));

outerDataList.DataSource = ds.Tables[0];

outerDataList.DataBind();

}

protected void outerRep_ItemDataBound(object sender, DataListItemEventArgs e)

{

if (e.Item.ItemType == ListItemType.Item)

{

DataRowView drv = e.Item.DataItem as DataRowView;

DataList innerDataList = e.Item.FindControl("innerDataList") as DataList;

innerDataList.DataSource = drv.CreateChildView("CategoriesRelation");

innerDataList.DataBind();

}

Now run the application and test it.

The above output displays subcategory according to the category.

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