Display hierarchical data by using nested Repeater controls and Visual C# .NET

Άρθρο
05/08/2022

This article provides information about how to display hierarchical data by using nested Repeater controls and Visual C# .NET.

Original product version: Visual C#
Original KB number: 306154

Summary

This article describes how to use nested Repeater controls to display hierarchical data. You can apply this concept to other list-bound controls.

This article refers to the following Microsoft .NET Framework Class Library namespaces:

System.Data
System.Data.SqlClient

Bind to the parent table

Start Visual Studio .NET.
On the File menu, point to New, and then click Project.
Click Visual C# Projects under Project Types, and then click ASP.NET Web Application under Templates.
In the Location box, delete the WebApplication#, and then type NestedRepeater. If you use the local server, leave the server name as http://localhost. The http://localhost/NestedRepeater path appears in the Location box. Click OK.
In Solution Explorer, right-click the NestedRepeater project name node, point to Add, and then click Add Web Form.
To name the Web Form, type NestedRepeater, and click Open.
The new Web Form is created. It opens in Design View in the Integrated Development Environment (IDE) of Visual Studio .NET. From the Toolbox, select the Repeater control, and then drag it to the Web Form page.
Change the ID property of this Repeater control to parentRepeater.
Switch to the HTML view for this Web Form. To do so, click the HTML tab in the lower-left corner of the Designer. The Repeater control generates the following HTML code:
```
<asp:Repeater id="parentRepeater" runat="server"></asp:Repeater>
```

Add the following code in the Repeater tags:

<itemtemplate>
    <b>
        <%# DataBinder.Eval(Container.DataItem, "au_id") %>
    </b>
    <br>
</itemtemplate>

After you do that, the HTML code for the Repeater is as follows:

<asp:Repeater id="parentRepeater" runat="server">
    <itemtemplate>
        <b>
            <%# DataBinder.Eval(Container.DataItem, "au_id") %>
        </b>
        <br>
    </itemtemplate>
</asp:Repeater>

In Solution Explorer, right-click NestedRepeater.aspx, and then click View Code to switch to the NestedRepeater.aspx.cs code-behind file.
Add the following namespace declaration to the top of the file:
```
using System.Data;
using System.Data.SqlClient;
```

Add the following code to the Page_Load event to create a connection to the Pubs database, and then to bind the Authors table to the Repeater control:

 public void Page_Load(object sender, EventArgs e)
 {
     //Create the connection and DataAdapter for the Authors table.
     SqlConnection cnn = new SqlConnection("server=(local);database=pubs; Integrated Security=SSPI");
     SqlDataAdapter cmd1 = new SqlDataAdapter("select * from authors",cnn);

     //Create and fill the DataSet.
     DataSet ds = new DataSet();
     cmd1.Fill(ds,"authors");
     //Insert code in step 4 of the next section here.
     //Bind the Authors table to the parent Repeater control, and call DataBind.
     parentRepeater.DataSource = ds.Tables["authors"];
     Page.DataBind();

     //Close the connection.
     cnn.Close();
 }

Note

You may have to modify the database connection string as appropriate for your environment.

Save all of the files.
In Solution Explorer, right-click the NestedRepeater.aspx, and then click Set As Start Page.
On the Build menu, click Build Solution to compile the project.
View the .aspx page in the browser, and then verify that the page works thus far. The output should appear as follows:
```
172-32-1176
213-46-8915
238-95-7766
267-41-2394
...
```

Bind to the child table

In the HTML view of the NestedRepeater.aspx page, locate the following line of code:

<b>
    <%# DataBinder.Eval(Container.DataItem, "au_id") %>
</b>
<br>

Add the following code after this code:

<asp:repeater id="childRepeater" runat="server">
    <itemtemplate>
        <%# DataBinder.Eval(Container.DataItem, "[\"title_id\"]")%>
        <br>
    </itemtemplate>
</asp:repeater>

This new code adds a second Repeater control to the ItemTemplate property of the parent Repeater control.

Set the DataSource property for the child Repeater control as follows:

<asp:repeater ... datasource='<%# ((DataRowView)Container.DataItem).Row.GetChildRows("myrelation") %>' >

After you set the DataSource property for the child Repeater control, the HTML code for the two Repeater controls (parent and child) appears as follows:

<asp:Repeater id="parentRepeater" runat="server">
    <itemtemplate>
        <b>
            <%# DataBinder.Eval(Container.DataItem, "au_id") %>
        </b>
        <br>
        <asp:repeater id="childRepeater" runat="server"
        datasource='<%# ((DataRowView)Container.DataItem).Row.GetChildRows("myrelation") %>' >
            <itemtemplate>
                <%# DataBinder.Eval(Container.DataItem, "[\"title_id\"]")%><br>
            </itemtemplate>
        </asp:Repeater>
    </itemtemplate>
</asp:Repeater>

Add the following page directive to the top of the page:
```
<%@ Import Namespace="System.Data" %>
```

In the code-behind page, replace the following line in the Page_Load event:

//Insert code in step 4 of the next section here.

//Create a second DataAdapter for the Titles table.
SqlDataAdapter cmd2 = new SqlDataAdapter("select * from titleauthor",cnn);
cmd2.Fill(ds,"titles");

//Create the relation between the Authors and Titles tables.
ds.Relations.Add("myrelation",
ds.Tables["authors"].Columns["au_id"],
ds.Tables["titles"].Columns["au_id"]);

This adds the Titles table to the DataSet, and then adds the relationships between the Authors and Titles tables.

Save and compile the application.
View the page in the browser, and then verify that the page works so far. The output should appear as follows:
```
172-32-1176
PS3333
213-46-8915
BU1032
BU2075
238-95-7766
PC1035
267-41-2394
BU1111
TC7777
```

Nestedrepeater.aspx code

<%@ Page language="c#" Codebehind="NestedRepeater.aspx.cs" AutoEventWireup="false" Inherits="NestedRepeater.NestedRepeater" %>
<%@ Import Namespace="System.Data" %>

<html>
    <body>
        <form runat=server>
            <!-- start parent repeater -->
            <asp:repeater id="parentRepeater" runat="server">
                <itemtemplate>
                    <b>
                        <%# DataBinder.Eval(Container.DataItem,"au_id") %>
                    </b>
                    <br>
                    <!-- start child repeater -->
                    <asp:repeater id="childRepeater" datasource='<%# ((DataRowView)Container.DataItem).Row.GetChildRows("myrelation") %>' runat="server">
                        <itemtemplate>
                            <%# DataBinder.Eval(Container.DataItem, "[\"title_id\"]")%><br>
                        </itemtemplate>
                    </asp:repeater>
                    <!-- end child repeater -->
                </itemtemplate>
            </asp:repeater>
            <!-- end parent repeater -->
        </form>
    </body>
</html>

Nestedrepeater.aspx.cs code

using System;
using System.Data;
using System.Data.SqlClient;
using System.Web;
using System.Web.SessionState;
using System.Web.UI;
using System.Web.UI.WebControls;

namespace NestedRepeater
{
    public class NestedRepeater : System.Web.UI.Page
    {
        protected System.Web.UI.WebControls.Repeater parentRepeater;
        public NestedRepeater()
        {
            Page.Init += new System.EventHandler(Page_Init);
        }
        public void Page_Load(object sender, EventArgs e)
        {
            //Create the connection and DataAdapter for the Authors table.
            SqlConnection cnn = new SqlConnection("server=(local);database=pubs; Integrated Security=SSPI ;");
            SqlDataAdapter cmd1 = new SqlDataAdapter("select * from authors",cnn);

            //Create and fill the DataSet.
            DataSet ds = new DataSet();
            cmd1.Fill(ds,"authors");

            //Create a second DataAdapter for the Titles table.
            SqlDataAdapter cmd2 = new SqlDataAdapter("select * from titleauthor",cnn);
            cmd2.Fill(ds,"titles");

            //Create the relation bewtween the Authors and Titles tables.
            ds.Relations.Add("myrelation",
            ds.Tables["authors"].Columns["au_id"],
            ds.Tables["titles"].Columns["au_id"]);

            //Bind the Authors table to the parent Repeater control, and call DataBind.
            parentRepeater.DataSource = ds.Tables["authors"];
            Page.DataBind();

            //Close the connection.
            cnn.Close();
        }
        private void Page_Init(object sender, EventArgs e)
        {
            InitializeComponent();
        }
        private void InitializeComponent()
        {
            this.Load += new System.EventHandler(this.Page_Load);
        }
    }
}

More information

For more information, see Repeater Web Server Control.