nested-binding.aspx

ASP.NET Web Forms Techniques

<%@ Page Language="C#" EnableViewState="True" EnableSessionState="True" SmartNavigation="False"%>
<%@ Import Namespace="System.Data"%>
<%@ Import Namespace="System.Data.SqlClient"%>


<script runat="server">
// -------------------------------------------------------------------

// page-level variable to hold DataSet of values from database
DataSet oCarsDS;

// page-level variable to hold random number generator
Random oRandom = new Random();

// -------------------------------------------------------------------

void Page_Load() {

  // get DataSet from function shown next in this page
  oCarsDS = GetCarDetailsDS("5");

  // display details of this vehicle
  dgrNesting.DataSource = oCarsDS.Tables["CarDetails"].DefaultView;
  dgrNesting.DataBind();

}

// -------------------------------------------------------------------

DataSet GetCarDetailsDS(String sCarID) {
// function to get selection of car details in a DataSet

  // to hold DataSet for the results
  DataSet dsCarDetail = null;

  // to hold stored procedure names
  String sCarProcName = "GetAllCarDetails";
  String sColorProcName = "GetAllCarColors";
  String sExtrasProcName = "GetAllCarExtras";

  String sConnect = ConfigurationSettings.AppSettings["XroxCarsConnectString"];
  SqlConnection sqlConn = new SqlConnection(sConnect);
  SqlCommand sqlComm = new SqlCommand(sCarProcName, sqlConn);
  sqlComm.CommandType = CommandType.StoredProcedure;

  try {

    // create a new empty DataSet for the results
    dsCarDetail = new DataSet();

    // and fill it from the database
    sqlComm.Parameters.Add("@CarID", sCarID);
    SqlDataAdapter daCarDetail = new SqlDataAdapter(sqlComm);
    sqlConn.Open();
    daCarDetail.Fill(dsCarDetail, "CarDetails");
    sqlComm.CommandText = sColorProcName;
    daCarDetail.Fill(dsCarDetail, "CarColors");
    sqlComm.CommandText = sExtrasProcName;
    daCarDetail.Fill(dsCarDetail, "CarExtras");

  }
  catch (Exception e) {
    return null;
  }
  finally {
    sqlConn.Close();
  }

  return dsCarDetail;

}

// -------------------------------------------------------------------

void FillLists(object oSender, DataGridItemEventArgs oArgs) {
// runs when the OnItemDataBound event occurs
// used to bind nested list controls and select values
// in this example, values selected at random but could come from rows

  // make sure its an Item or AlternatingItem row
  if (oArgs.Item.ItemType == ListItemType.Item || oArgs.Item.ItemType == ListItemType.AlternatingItem) {

    // get references to the three list controls and Image in this row
    RadioButtonList oRadioList = (RadioButtonList)oArgs.Item.FindControl("radEngine");
    CheckBoxList oCheckList = (CheckBoxList)oArgs.Item.FindControl("chkExtras");
    DropDownList oDropList = (DropDownList)oArgs.Item.FindControl("selColor");
    Image oImage = (Image)oArgs.Item.FindControl("imgColor");

    // set DataSource and DataBind the RadioButtonList control
    oRadioList.DataSource = oCarsDS.Tables["CarDetails"].DefaultView;
    oRadioList.DataTextField = "EngineName";
    oRadioList.DataValueField = "EngineID";
    oRadioList.DataBind();

    // set DataSource and DataBind the CheckBoxList control
    oCheckList.DataSource = oCarsDS.Tables["CarExtras"].DefaultView;
    oCheckList.DataTextField = "ExtraText";
    oCheckList.DataBind();

    // set DataSource and DataBind the DropDownList control
    oDropList.DataSource = oCarsDS.Tables["CarColors"].DefaultView;
    oDropList.DataTextField = "Color";
    oDropList.DataValueField = "ColorID";
    oDropList.DataBind();


    // create random values for the controls
    int iEngine = oRandom.Next(0, 3);
    int iExtra1 = oRandom.Next(0, 6);
    int iExtra2 = oRandom.Next(0, 6);
    int iExtra3 = oRandom.Next(0, 6);
    int iColor = oRandom.Next(0, 8);

    // select RadioButton in "Engines" RadioButtonList control
    oRadioList.SelectedIndex = iEngine;

    // select three CheckBoxes in "Extras" CheckBoxList control
    oCheckList.Items[iExtra1].Selected = true;
    oCheckList.Items[iExtra2].Selected = true;
    oCheckList.Items[iExtra3].Selected = true;

    // could select item(s) in a list control by iterating
    // through values to find a match for a specific value
    foreach (ListItem oItem in oDropList.Items) {
      if (oItem.Value == iColor.ToString()) oItem.Selected = true;
    }

    // or instead, if we know the SelectedIndex value (as here)
    oDropList.SelectedIndex = iColor;

    // get text from drop-down list and use to set Image source
    String sColorName = oDropList.SelectedItem.Text;
    oImage.ImageUrl = "../xroxcars/images/colors/" + sColorName + ".gif";

  }

}

// -------------------------------------------------------------------
</script>

<!doctype html public "-//W3C//DTD HTML 3.2 Final//EN">
<html>
<head>
<basefont size="2" face="Tahoma,Arial,Helvetica,sans-serif">
</head>
<body bgcolor="#ffffff" class="body-text">

<form runat="server">

  <asp:DataGrid id="dgrNesting" runat="server" AutoGenerateColumns="False"
       CellPadding="4"
       Font-Size="10"
       Font-Name="Tahoma,Arial,Helvetica,sans-serif"
       HeaderStyle-HorizontalAlign="center"
       HeaderStyle-BackColor="#b50055"
       HeaderStyle-ForeColor="#ffffff"
       HeaderStyle-Font-Bold="True"
       ItemStyle-HorizontalAlign="center"
       SelectedItemStyle-BackColor="#ffffcc"
       OnItemDataBound="FillLists">

    <Columns>

      <asp:TemplateColumn HeaderText="Select Engine">
        <ItemTemplate>
          <asp:RadioButtonList style="font-size:12px" id="radEngine" runat="server" />
        </ItemTemplate>
      </asp:TemplateColumn>

      <asp:TemplateColumn HeaderText="Select Extras">
        <ItemTemplate>
          <asp:CheckBoxList style="font-size:12px" id="chkExtras" runat="server" />
        </ItemTemplate>
      </asp:TemplateColumn>

      <asp:TemplateColumn HeaderText="Select Color">
        <ItemTemplate>
          <asp:DropDownList style="font-size:12px" id="selColor" runat="server" /><p />
          <asp:Image id="imgColor" border="1" runat="server" />
        </ItemTemplate>
      </asp:TemplateColumn>

    </Columns>

  </asp:DataGrid>

</form>

</body>
</html>