How to reference a UserControl from a DataGrid

[This was originally posted at http://timstall.dotnetdevelopersjournal.com/how_to_reference_a_usercontrol_from_a_datagrid.htm]

Sometimes you need to have a UserControl in a DataGrid, and sometime you also need to reference that control to either get/set its values. In ASP.Net, this is straight forward.

First let's create a UserControl and host Aspx page. The important sections are below, but you can download it here.

UserControl

Html:

<%@ Control Language="c#" AutoEventWireup="false" Codebehind="UCSimple.ascx.cs" Inherits="UIDemo.UC.UCSimple" TargetSchema="http://schemas.microsoft.com/intellisense/ie5"%> <asp:TextBox id="TextBox1" runat="server">asp:TextBox> <asp:Button id="Button1" runat="server" Text="Button">asp:Button> <asp:Label id="Label1" runat="server">Labelasp:Label>

CodeBehind:

private void Page_Load(object sender, System.EventArgs e) {     // Put user code to initialize the page here } private void Button1_Click(object sender, System.EventArgs e) {     this.Label1.Text = this.TextBox1.Text; } public string TextValue {     get     {         return this.TextBox1.Text;     }     set     {         this.TextBox1.Text = value;     } }

Host Aspx Page

CodeBehind

private void Page_Load(object sender, System.EventArgs e) {     // Put user code to initialize the page here     if (!Page.IsPostBack)     {         string[] astr = new string[] {"aaa","bbb","ccc"};         this.DataGrid1.DataSource = astr;         this.DataGrid1.DataBind();     } } private const int _UCColumn = 0; private const int _UCControlPosition = 1; private void Button1_Click(object sender, System.EventArgs e) {     int intRow = Convert.ToInt32(this.TxtRow.Text);     UCSimple uc = (UCSimple)this.DataGrid1.Items[intRow].Cells[_UCColumn].Controls[_UCControlPosition];     uc.TextValue = this.TxtSet.Text; } private void BtnGet_Click(object sender, System.EventArgs e) {     int intRow = Convert.ToInt32(this.TxtRow.Text);     UCSimple uc = (UCSimple)this.DataGrid1.Items[intRow].Cells[_UCColumn].Controls[_UCControlPosition];     this.LblGet.Text = uc.TextValue; } private void DataGrid1_SelectedIndexChanged(object sender, System.EventArgs e) {     //Then this fires too.     e = e; } private void DataGrid1_ItemCommand(object source, System.Web.UI.WebControls.DataGridCommandEventArgs e) {     //First this fires     e = e;     UCSimple uc = (UCSimple)e.Item.Cells[_UCColumn].Controls[_UCControlPosition];     this.LblGet.Text = uc.TextValue; }

Get the UserControl

We can reference the control absolutely:

UCSimple uc = (UCSimple)this.DataGrid1.Items[intRow].Cells[_UCColumn].Controls[_UCControlPosition];

or from the argument in an individual row.

UCSimple uc = (UCSimple)e.Item.Cells[_UCColumn].Controls[_UCControlPosition];

Note what's going on:

1. Get the row (via .Items[intRow] or just e.Item)
2. Then get the column (via .Cells[_UCColumn] )
3. Then get the control within that cell - a single cell can have multiple controls.
4. Then cast that as the UserControl type that you need.
5. Then reference the get/set of any public property.

This will allow you to reference user controls from either outside the grid, or with respect to any row.